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    Table of Contents
  1. Intro
  2. Design
    1. Style
    2. Comfort
    3. Controls
    4. Stability
    5. Portability
    6. Case
    7. Build Quality
    8. Breathability
    9. Cable
    10. Front
    11. Angled
    12. Side
    13. Rear
    14. Top
  3. Sound
    1. Bass
    2. Mid
    3. Treble
    4. Frequency Response Consistency
    5. Raw Frequency Response
    6. Soundstage
    7. Imaging
    8. Total Harmonic Distortion
  4. Isolation
    1. Noise Isolation
    2. Leakage
  5. Microphone
    1. Recording Quality
    2. Noise Handling
  6. Active Features
    1. Wireless Range
    2. Latency
    3. Battery
    4. App Support
  7. In the box
  8. Conclusion
  9. Q&A
Reviewed on Oct 24, 2017 , Marc Henney, Yannick Khong

Superlux HD 681 EVO
HEADPHONES REVIEW

Usage Ratings - Version 1.1
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Test Benches:

  • 1.1: Summer 2017
  • 1.0: Winter 2017
  • 0.9: Winter 2016
5.9Mixed Usage
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What it is This is the combination of the different use cases to evaluate how versatile the headphones are. Therefore an everyday headphone should be well-rounded enough to adapt to most situations and environments without significant losses in sound quality, design ergonomics or isolation.
Score components:
7.5Critical Listening
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What it is The level of audio fidelity a headphone can reproduce. Therefore a balanced and true representation of bass, mids, treble, soundstage and imaging, as well as a comfortable listening experience, is essential for critical listening.
Score components:
5.2Commute/Travel
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What it is How well the headphones handle the loud environments involved in commuting or traveling. Therefore your listening experience should be comfortable, hassle-free and as isolated from noise as possible.
5.4Sports/Fitness
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What it is How well-adapted the headphones are, to use while doing sports or strenuous exercise. Therefore the headphones should not be too cumbersome and deliver a stable and comfortable listening experience.
5.5Office
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What it is How well the headphones can deliver a comfortable and isolated listening experience in an office-like environment. They should not leak much and should block the noise of a busy office.
Score components:
Type : Over-ear
Enclosure : Semi-Open
Wireless : No
Noise-Cancelling : No
Mic : No
Transducer : Dynamic

The Superlux HD 681 EVO are a slightly better-designed version of the HD 681. They sound about the same although the EVO has a bit more bass. They're also budget and affordable headphones for the quality of audio reproduction they deliver. Unfortunately, they don't have the best build quality. They feel cheap and flimsy, and the semi-open design means they won't be suitable for all environments.

See our recommendations for the best Critical Listening Headphones.
Test Results
Design 6.2
Sound 7.7
Isolation 4.0
Microphone 0
Active Features 2.7
Pros
  • Good audio reproduction.
  • Lightweight design.
Cons
  • Plasticky build quality.
  • Sensitive to noisy environments.

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6.2

Design

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Score components:
Superlux HD 681 EVO Design Picture

The Superlux HD 681 EVO are a somewhat improved version of the HD 681 with a detachable cable. The headband design is slightly different but is still as comfortable HD 681 and better than the HD 668B. Unfortunately, they don't have the best build quality. They're flimsy, plasticky and feel a bit cheap. They also have a bulky design that's impractical and bit too cumbersome for sports or outdoor use. They won't be suitable to run with, they have no control scheme, and they're not portable.

Style
Superlux HD 681 EVO Design Picture 2

The HD 681 EVO are decent-looking but plasticky headphones. They have a completely different ear cup design to the HD 681 and 668. They're still semi-open ear cups, but the vents are slightly hidden giving these headphones a more closed-back look. The headband strap is also a bit different but has the same fit and comfort level as the original HD 681. However, unlike the other Superlux headphones these come in two color schemes. An understated and glossy black finish and a more flashy white that will stand out but may not be for everyone. They're also a bit bulky and cumbersome to wear and use outdoors.

7.5 Comfort
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What it is: Adjustability and degrees of freedom, pressure, stiffness and weight.
When it matters: When the headphones are going to be used for long durations.
Score components: Subjectively assigned
Superlux HD 681 EVO Comfort Picture
Weight : 0.61 lbs
Clamping Force
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What it is: The force that the headphones exert on your head, once you have them on. This is purely a measurement of the force applied, which does not take into account the earpad's surface area and the resulting pressure you will feel, on or around your ears.
When it matters: The tighter the headphones, the more force they put on your head. This can get uncomfortable or cause pain and soreness during long listening sessions.
:
1.2 lbs

The Superlux HD 681 EVO have the same strap design as the HD 681 which makes them more comfortable than the HD 668B. They're a bit tighter on the head than the original 681, but the large ear cups and self-adjusting headband fits comfortably for most. They may get a little tiring during long listening sessions, but they're lightweight and come with additional softer pads that feel better on the skin thanks to the microfiber coating.

0 Controls
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What it is: The control scheme of the headphones, the number of functions provided, button layout and ergonomics as well as the quality of tactile feedback.
When it matters: If you want to control volume, pause your music or make phone calls without directly interacting with your audio device.
Ease of use : N/A
Feedback : N/A
Call/Music Control : No
Volume Control : No
Microphone Control : N/A
Noise Canceling Control : N/A
Talk-Through : N/A
Additional Buttons : N/A

6.5 Stability
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What it is: How the headphones are designed to prevent them from slipping off your ears or falling off your head.
When it matters: If you plan on using the headphones while doing sports or other physical activities that requires a lot of movement.
Score components: Subjectively assigned
Superlux HD 681 EVO Stability Picture

The HD 681 EVO are as tight on the head as the HD 668 but also have a detachable cable. This makes them moderately stable, especially under casual conditions. However, they're not designed or meant for sports. They will quickly fall if you use them while doing any physical activities and won't be good headphones to work out with or to take to the gym.

5.5 Portability
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What it is: The volume of space occupied by the headphones when folded into their most compact format.
When it matters: If you're often on the move and need to carry your headphones in a bag, purse , or pocket.
Score components:
Superlux HD 681 EVO Portability Picture
L : 7.5 "
W : 7.2 "
H : 3.5 "
Volume : 189 Cu. Inches
Stand required : N/A

The HD 681 EVO are bulky, cumbersome headphones that do not fold into a more compact format. The ear cups do not lay flat either which makes them difficult to carry around on your person without a bag.

5.5 Case
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What it is: The provided carrying options to protect your headphones when transporting them.
When it matters: To prevent damaging your headphones, if you often carry them in your bag or pocket.
Score components: Subjectively assigned
Superlux HD 681 EVO Case Picture
Type : Pouch
L : N/A
W : N/A
H : N/A
Volume : N/A

Comes with a somewhat, rugged pouch that will shield the headphones from scratches and minor water exposure. However, it will not protect your headphones against drops and impacts.

6.0 Build Quality
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What it is: Durability, material quality, cheap/expensive feel.
When it matters: When the headphones are going to be used by multiple users (classes/studios), by children, in tough conditions, on a daily basis, or for exercise.
Score components: Subjectively assigned
Superlux HD 681 EVO Build Quality Picture

The HD 681 EVO like the HD 681 and HD 668B feel cheaply made and plasticky. They're budget headphones which show in their build quality. They're almost entirely made out of plastic that doesn't feel dense or durable. They won't break if you accidentally drop them once or twice, and they have a detachable cable that you can replace, but their overall build quality isn't particularly sturdy.

6.6 Breathability
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What it is: How hot the headphones get when you wear them for an extended period of time.
When it matters: If you often have long listening sessions or use your headphones while doing physical activities like running or working out.
Score components:
Superlux HD 681 EVO Breathability Before Picture Superlux HD 681 EVO Breathability After Picture
Avg.Temp.Difference : 5.2 C

Cable
Superlux HD 681 EVO Cable Picture
Detachable :
Length : 8.4 ft
Connection : 1/8" TRS

Comes with two 1/8" TRS audio cables.

Front
Angled
Side
Rear
Top
7.7

Sound

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What it is: How accurately the audio is reproduced. The tests are performed with the headphones' most commonly used features enabled (noise-cancelling, wireless, etc.)
Superlux HD 681 EVO Frequency Response

The Superlux HD 681 EVO are a good sounding pair of semi-open over-ear headphones. They have a deep and powerful bass, a balanced mid range, and a good treble. They also image well and have an average soundstage. However, their bass delivery can vary from person to person, their mid range is slightly recessed, and their treble could sound a bit too sharp on overly bright tracks.

8.5 Bass
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What it is: Frequency Response from 20Hz-250Hz
When it matters: When the material is heavy on bass frequencies, such as those of kick drums and bass guitar.
Score components:
Superlux HD 681 EVO Bass
Std. Err.
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What it is: The amount of deviation (weighted standard error) in bass frequency response (20Hz-250Hz) as compared to a target response that would sound perfectly balanced to most people.
When it matters: When a balanced and neutral (reference) bass performance is desired.
Good value: <4dB
Noticeable difference: 0.1dB
:
2.2 dB
Low-Frequency Extension
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What it is: The lowest frequency at which the frequency response reaches -3dB of the target response.
When it matters: Shows how extended the bass is.
Good value: <40Hz
Noticeable difference: 5Hz
:
10 Hz
Low-Bass
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What it is: The average amount of over/under-emphasis in frequency response from 20Hz-60Hz.
When it matters: Kick drums and low frequency effects get their 'thump' from this range. Mostly felt than heard.
Good value: +/-3dB
Noticeable difference: 0.1dB
:
2.94 dB
Bass
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What it is: The average amount of over/under-emphasis in frequency response from 60Hz-120Hz.
When it matters: Melodic bass instruments have most of their fundamental frequencies in this range. This is where the 'body' and 'punch' of the bass sits.
Good value: +/-3dB
Noticeable difference: 0.1dB
:
2.55 dB
High-Bass
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What it is: The average amount of over/under-emphasis in frequency response from 120Hz-250Hz.
When it matters: Most instruments get their warmth and full-ness from this range. When over-emphasized, mixes tend to get muddy and boomy.
Good value: +/-3dB
Noticeable difference: 0.1dB
:
0.35 dB

Great bass range performance. Low-bass, which is responsible for rumble and thump is extended down to 10Hz. Additionally, both low-bass and bass are overemphasized by about 2.5dB, making these headphones slightly bass-heavy.

8.4 Mid
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What it is: Frequency Response from 250Hz-2KHz
When it matters: When the material is heavy on mid-range frequencies. This is the case for the majority of audio content.
Score components:
Superlux HD 681 EVO Mid
Std. Err.
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What it is: The amount of deviation (weighted standard error) in mid frequency response (250Hz-2.5KHz) as compared to a target response that would sound perfectly balanced to most people.
When it matters: When a balanced and neutral (reference) mid performance is desired.
Good value: <4dB
Noticeable difference: 0.1dB
:
2.19 dB
Low-Mid
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What it is: The average amount of over/under-emphasis in frequency response from 250Hz-500Hz.
When it matters: Most instruments have their fundamentals or low harmonics in this range. Over-emphasis in this range sounds muddy and cluttered. Under-emphasis, thins out the vocals and lead instruments.
Good value: +/-3dB
Noticeable difference: 0.1dB
:
-1.76 dB
Mid
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What it is: The average amount of over/under-emphasis in frequency response from 500Hz-1KHz.
When it matters: This range is occupied mostly by upper harmonics. Over-emphasis sounds forward and boxy. Under-emphasis pushes instruments to the back of the mix.
Good value: +/-3dB
Noticeable difference: 0.1dB
:
-2.3 dB
High-Mid
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What it is: The average amount of over/under-emphasis in frequency response from 1KHz-2KHz.
When it matters: Most instruments, especially vocals, get their intensity and clarity from this range. Over-emphasis sounds honky and harsh, under-emphasis sounds weak and distant.
Good value: +/-3dB
Noticeable difference: 0.1dB
:
-1.33 dB

Very good mid range performance. The response is mostly flat, but underemphasized by an average of 2dB. This results in an even but recessed mid range which could be slightly overpowered by the bass range.

7.8 Treble
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What it is: Frequency Response from 2KHz-20KHz
When it matters: When the material is heavy on high-range frequencies, such as voice, cymbals, and any other material where brightness, brilliance and airiness is desired.
Score components:
Superlux HD 681 EVO Treble
Std. Err.
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What it is: The amount of deviation (weighted standard error) in treble frequency response (2.5KHz-20KHz) as compared to a target response that would sound perfectly balanced to most people.
When it matters: When a balanced and neutral (reference) treble performance is desired.
Good value: <4dB
Noticeable difference: 0.1dB
:
3.66 dB
Low-Treble
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What it is: The average amount of over/under-emphasis in frequency response from 2KHz-5KHz.
When it matters: Almost all instruments rely on this range for their presence, detail, and articulation. Over-emphasis can sound harsh and painful. Under-emphasis hurts the comprehensibility of vocals and lead instruments.
Good value: +/-3dB
Noticeable difference: 0.1dB
:
-1.71 dB
Treble
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What it is: The average amount of over/under emphasis in frequency response from 5KHz-10KHz.
When it matters: This is the sibilance range. Cymbals, vocals, and lead instruments rely on this range for brightness and presence. Over-emphasis sounds piercing and painful, under-emphasis sounds dull and lispy.
Good value: +/-3dB
Noticeable difference: 0.1dB
:
0.5 dB
High-Treble
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What it is: The average amount of over/under-emphasis in frequency response from 10KHz-20KHz.
When it matters: This range gives brilliance and airiness to the sound. Over-emphasis sounds hissy, under-emphasis sounds closed-up and lifeless.
Good value: +/-3dB
Noticeable difference: 0.1dB
:
-0.45 dB

Good treble range performance. The narrow 5dB dip centered around 4KHz will have a small negative effect on detail and presence of vocals/leads. The peak around 10KHz could make S and T sounds a bit sharp and piercing on overly bright tracks.

7.3 Frequency Response Consistency
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What it is: The amount of deviation of each frequency response pass, from the average frequency response.
When it matters: Shows how consistently the headphones perform after re-positioning them.
Score components:
Superlux HD 681 EVO Consistency L Superlux HD 681 EVO Consistency R
Avg. Std. Deviation
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What it is: The average amount of deviation in frequency response of 5 re-seats, from the average frequency response.
When it matters: Shows how consistently the headphones perform after re-positioning them.
Good value: <0.5
Noticeable difference: 0.1
:
0.54 dB

Decent consistency. The HD HD 681 EVO shows good consistency in its treble range, with the maximum deviation of +/-3dB below 10KHz. In the bass range however, the 681 EVO is less consistent in its bass delivery across different humans, and could even be affected by wearing glasses..

6.5 Soundstage
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What it is: Soundstage qualities are not inherent to the audio content, the headphones have to 'create' them rather than 'reproduce' them. They determine whether the sound is perceived to be coming from inside or in front of the head, how open and spacious the soundstage is, how much the headphones acoustically interact with the environment, and how strong the phantom center is.
When it matters: When an accurately produced, large and spacious soundstage, similar to that of a stereo loudspeaker setup is desired.
PRTF Error
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What it is: The average amount of deviation in Pinna-Related Transfer Function of the headphones, compared to that of a loudspeaker. Whether the soundstage is perceived to be unnatural, located inside or in front of the head, is dependent on this quality. The more the headphones activate the HRTF resonances of the ear (similar to what loudspeakers do), the more the soundstage will be pulled out from inside the listener's head. This quality affects both stereo and mono content.
When it matters: When a natural, in-the-front soundstage is desired, similar to that of a loudspeaker.
Good value: <5
Noticeable difference: 0.5
:
6.8 dB
Openness
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What it is: How open the headphones are, and how open and spacious they sound. This quality affects both stereo and mono content. This test differentiates between acoustically and electronically produced crosstalk and only takes the acoustically generated crosstalk into account. This value is the inverse of the Noise Isolation test score.
When it matters: When an open, wide and roomy sound is desired. A value of 10 indicates a fully open headphone, and a value of 0 indicates a fully closed headphone.
Good value: >7.5
Noticeable difference: 0.5
:
7.3
Acoustic Space Excitation
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What it is: How loud the headphones are, and how much they excite their environment acoustically. If the headphones are loud and open enough, the sound leaking from the headphones takes some of the characteristic of its environment (reflections/reverb) before reflecting back into the open headphones and to the listener's ears. This quality affects both stereo and mono content. This value is the inverse of the Leakage test score.
When it matters: When an open, wide and roomy sound is desired.
Good value: >7.5
Noticeable difference: 0.5
:
6.5
Correlated Crosstalk
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What it is: How strong and solid the phantom center is. This is mostly a stereo quality and its effects on mono content are minimal. This test is sensitive to the phase of the crosstalk and whether it is produced acoustically or electronically.
When it matters: When a true reproduction of the stereo image is desired. A value of 0 indicates no crosstalk, or that the existing crosstalk is not correlated enough to affect the phantom center. A negative score means the crosstalk is out of phase with the original signal, resulting in a slightly wider stereo image at the expense of creating a 'hole' at the center of the stereo field. A positive score means the crosstalk is in phase and positively affecting the phantom center.
Good value: >1dB
Noticeable difference: 0.3dB
:
0.0 dB

Average soundstage performance. Due to their semi-open design, the 681 EVO has a relatively open sounding soundstage. However, because of their small and shallow ear cups, they don't activate the pinna resonances like loudspeakers do.

8.1 Imaging
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What it is: Imaging qualities are inherent to the audio content, the headphones have to 'reproduce' them rather than 'create' them. They determine how accurately the objects are positioned in the stereo image, and how transparent the imaging is.
When it matters: When accurate positioning of the objects in the stereo image, and clear and transparent imaging is desired.
Superlux HD 681 EVO Phase Response
Phase Error
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What it is: The average amount of deviation in the phase, from the ideal flat response.
When it matters: When an accurate and transparent imaging is desired.
Good value: <60°
Noticeable difference: 10°
:
46.0 °
Driver Mismatch (Amplitude)
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What it is: The Left/Right balance of our test unit, that is, the amount of amplitude difference between the left and right drivers. This is not a design test, but a marker for manufacturing tolerance and ergonomics.
When it matters: When a properly balanced stereo image and low manufacturing tolerance is desired. A poor score indicates a noticeable difference in level between the left and right drivers.
Good value: <0.3dB
Noticeable difference: 0.1dB
:
0.35 dB
Driver Mismatch (Frequency)
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What it is: The amount of difference (Std. Err.) between the frequency response of the left and right drivers of our test unit. This is not a design test, but a marker for manufacturing tolerance and ergonomics.
When it matters: When an even and stable stereo image, as well as a low manufacturing tolerance, is desired. A poor score indicates there may be 'holes' in the stereo image at certain frequencies.
Good value: <2dB
Noticeable difference: 0.1dB
:
1.5 dB
Driver Mismatch (Phase)
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What it is: The amount of difference (Std. Err.) between the phase response of the left and right drivers of our test unit. This is not a design test, but a marker for manufacturing tolerance and ergonomics.
When it matters: When an even and stable stereo image, as well as a low manufacturing tolerance, is desired. A poor score indicates there may be inaccuracies in the stereo image reproduction at certain frequencies.
Good value: <90°
Noticeable difference: 30°
:
26.66 °

Very good imaging performance. Phase error is minimal, especially in the mid range. Additionally, the L/R drivers of our test unit where also quite well-matched.

6.8 Total Harmonic Distortion
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What it is: The subtle, unwanted frequencies (harmonics) produced alongside the intended frequencies.
When it matters: When clean and pure sound reproduction is desired, though its effect is not as noticable as frequency response.
Score components:
Superlux HD 681 EVO Distortion
Weighted THD @ 90
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What it is: The overall amount of harmonic distortion measured at 90dB SPL. To make the score more perceptually relevant, more weight is given to the higher frequencies.
When it matters: How pure the sound is at moderate listening levels.
Good value: <0.100
Noticeable difference: 0.1
:
2.401
Weighted THD @ 100
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What it is: The overall amount of harmonic distortion measured at 100dB SPL. To make the score more perceptually relevant, more weight is given to the higher frequencies.
When it matters: How pure the sound is at loud listening levels.
Good value: <0.300
Noticeable difference: 0.1
:
18.554

Average harmonic distortion performance. The amount of harmonic distortion in the bass range is elevated, however humans are less sensitive to low frequency harmonic distortion. On the other hand, the peaks around 1.5KHz and 4KHz could have a negative effect on the treble of these headphones by making it sound a bit harsh and brittle.

4.0

Isolation

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Score components:

The HD 681 EVO are not designed to block ambient noise. They have semi-open ear cups that create a more immersive soundstage but also leaks and lets noise seep into whatever you're listening to. This makes the HD 681 EVO not suitable for commuting or other loud environments although their isolation performance is a bit better than the HD 668B or the original 681. Also since they leak quite a bit they won't be ideal for use in quieter settings if you don't want to distract those around you.

4.2 Noise Isolation
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What it is: How much outside noise is blocked out by putting the headphones on.
When it matters: If the headphones are going to be used in a noisy envinronment (airplane, subway, etc.)
Score components:
Superlux HD 681 EVO Noise Isolation
Overall Attenuation
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What it is: The overall amount of environmental noise reduction in dB.
When it matters: In loud envinronments like planes, trains, offices, etc.
Good value: <-20dB
Noticeable difference: 1dB
:
-8.72 dB
Bass
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What it is: The overall amount of noise isolation in the bass range (20Hz-250Hz).
When it matters: When the outside noise is bass-heavy, like in airplanes.
Good value: <-15dB
Noticeable difference: 1dB
:
-0.18 dB
Mid
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What it is: The overall amount of noise isolation in the mid-range (250Hz-2.5KHz).
When it matters: When the environment's noise is mid-heavy, like in an office.
Good value: <-15dB
Noticeable difference: 1dB
:
-1.93 dB
Treble
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What it is: The overall amount of noise isolation in the treble range (2.5KHz-20KHz).
When it matters: When the environment's noise is treble-heavy. Although uncommon, areas with sharp sounds fall under this category.
Good value: <-30dB
Noticeable difference: 1dB
:
-23.91 dB
Self-Noise
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What it is: The amount of noise created by the active electronics of the headphones (if applicable), measured from 300Hz-20KHz. Applies mostly to wireless and noise-cancelling headphones.
When it matters: If too loud, it could become distracting when listening to quiet material like podcasts and audiobooks.
Good value: <16dB
Noticeable difference: 1dB
:
0 dB

Poor isolation. These headphones don't have active noise cancellation, and are also semi-open. Therefore, they don't isolate below 1KHz. Above that, they achieve about 24dB of isolation, which is about average.

3.5 Leakage
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What it is: The amount of sound bleeding out of the headphones.
When it matters: When the listener doesn't want people around them (in office, recording studio, etc.) to hear what is being listened to.
Score components:
Superlux HD 681 EVO Leakage
Overall Leakage @ 1ft
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What it is: The amount of sound leakage heard 1 foot away from the user, while the user is listening to a 100dB SPL signal.
When it matters: When you don't want people hear what you are listening to.
Good value: <35dB
Noticeable difference: 1dB
:
56.05 dB

Poor leakage performance. The significant portion of the leakage sits between 400Hz and 20KHz which is quite a broad range. The overall level of leakage is also loud.

0

Microphone

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What it is: The microphone section shows the quality of speech capture and transmission by the mic, as well as how well the microphone under test handles noisy environments.
When it matters: For your speech to be transmitted to and understood properly by the listener, the microphone needs to have a good recording quality. If the environment the microphone is being used in is noisy, a microphone with a good noise handling performance would be needed as well.
Score components:
0 Recording Quality
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What it is: Microphone recording quality shows how natural, neutral, extended and intelligible speech would be with the device under test, in a quiet environment.
When it matters: A microphone with a good recording quality ensures that the person listening to you would hear a full, clear, and easily understandable speech. Therefore, it is important whenever a good quality of speech transmission and intelligibility is needed.
Score components:
LFE
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What it is: Low-frequency extension shows how deep the bass response of the microphone is, and therefore, how deep and full your voice would sound to the listener. It is the lowest frequency at which the frequency response reaches -3dB of the target response.
When it matters: LFE is not a big factor in speech intelligibility and even speech recorded with a mic that has an LFE of 500Hz could still be easily understood. Therefore, it is mostly important if you are concerned with how deep and full your voice would be heard.
Good value: <150Hz
Noticeable difference: 30Hz
:
N/A
FR Std. Dev.
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What it is: Frequency Response Standard Deviation shows how accurately and balanced sound is captured by the microphone at each frequency. FR Std. Dev. is calculated between LFE and HFE, and the rest of the spectrum is ignored.
When it matters: A good frequency response is desired when a natural and neutral speech quality is desired. As opposed to HFE which is more a metric for speech intelligibility, frequency response could be considered as a metric for a natural and neutral sound.
Good value: >3.5dB
Noticeable difference: 0.5dB
:
N/A
HFE
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What it is: High-frequency extension is the highest frequency at which the frequency response reaches -3dB of the target response. It shows how extended the treble response of the microphone is.
When it matters: HFE is one the most important factors in speech intelligibility. The higher the HFE, the brighter, more open, and more extended the speech quality will be which makes it a lot easier to understand by the listener.
Good value: >8KHz
Noticeable difference: 1KHz
:
N/A
Weighted THD
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What it is: The unwanted frequencies (harmonics) produced alongside the intended frequencies, which cause deformation of an output signal compared to its input.
When it matters: When clean and pure sound reproduction is desired, though its effect is not as noticable as frequency response.
Good value: <1.5
Noticeable difference: 1.0
:
N/A
Gain
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What it is: Shows how much louder the microphone can go above our reference loudness level. The gain value is reported relative to our reference level, which is 94dB at a distance of 5cm from the mouth.
When it matters: A microphone with a high gain is important when the input signal (speech) is very quiet. For example when whispering, or talking on the phone in a library.
Good value: >18dB
Noticeable difference: 3dB
:
N/A

0 Noise Handling
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What it is: How well the microphone is able to separate speech from background noise, so that the transmission would include more voice and less noise.
When it matters: When a clean and intelligible speech transmission is desired in a noisy situation like talking on the phone on a busy street or on the bus.
Score components:
SpNR
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What it is: Speech to Noise Ratio is the difference in level between speech and background noise as heard by the listener
When it matters: If the microphone is going to be used in a noisy environment, it is important for it to be able to separate the speech from background noise, so the voice would be easily audible and understandable.
Good value: >24dB
Noticeable difference: 3dB
:
N/A

2.7

Active Features

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What it is: Headphones with active components that require a battery. This includes noise cancelling and wireless headphones that actively reduce noise or transmit audio via a wireless connection.
When it matters: How suitable the power and wireless specifications of an active headphone will be, depending on your listening habits. The range and/or discharge time of the active headphone you select will be important if you're often on the move or have long uninterrupted listening sessions.
Score components:

No active features.

0 Wireless Range
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What it is: Headphones that offer a cable-free listening experience over a wireless network, typically via Bluetooth or radio frequency.
When it matters: If you don't want to be limited by the length of an audio cable. This means having the freedom to move around in your home or office with a much greater range than an audio cable could provide, especially, if the Bluetooth source is heavy or difficult to carry.
Score components:
Type
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What it is: The type and version of the wireless network, the headphones use to connect to the audio source. This could either be Bluetooth or radio frequency.
When it matters: The Bluetooth version will determine how compatible the headphones are with your Bluetooth enabled devices. Typically, newer Bluetooth versions are backward compatible with older ones but may lack the additional features that more recent Bluetooth protocols provide.
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Wired Connection
Obstructed Range
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What it is: The range that the wireless headphones can reach before dropping any audio when the Bluetooth source was placed in another room.
When it matters: If you can't or prefer not to carry your Bluetooth source on you, while listening to your audio in an indoor environment. Although, the obstructed wireless range will slightly depend on your home or office layout.
Good value: >35ft
Noticeable difference: 5ft
:
N/A
Line of Sight Range
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What it is: The range that the wireless headphones can reach before dropping any audio when in direct line of sight of the Bluetooth device.
When it matters: If you can't or prefer not to carry your Bluetooth source on you, while listening to your audio in a large and open environment.
Good value: 170ft or more
Noticeable difference: 10ft
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N/A
NFC
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What it is: Near Field Communication technology that allows you to quickly, pair your headphones with your Bluetooth and NFC-enabled device.
When it matters: This makes pairing with an NFC-enabled device a lot easier than the typical and often tedious hold-to-pair procedure that most wireless headphones have.
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N/A

10 Latency
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What it is: The latency is how long it takes for audio to play through your headphones once the audio signal has been sent from a source.
When it matters: When gaming or watching movies. High latency means you will hear the audio much later than the images you see on screen.
Score components:
Base Latency
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What it is: The Base RF latency or the default sub-band coding (SBC) of most Bluetooth headphones.
When it matters: When watching videos a high latency can cause sync issues between the images you see and the audio you hear.
Good value: 50ms or less
Noticeable difference: 15ms
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0 ms
aptX Latency
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What it is: An audio coding algorithm (Codec) that improves bit rate efficiency. It reduces latency and improves sound quality over Bluetooth.
When it matters: For better sound quality if your often streaming music over Bluetooth. Also it slightly improves latency when watching videos with wireless headphones.
Good value: 50ms or less
Noticeable difference: 15ms
:
N/A
aptX(LL) Latency
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What it is: Low latency variation of aptX that significantly reduces sync issues between video and sound when using Bluetooth headphones.
When it matters: When watching videos or gaming latency is a lot more noticeable than just listening to music.
Good value: 50ms or less
Noticeable difference: 5ms
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N/A

Wired connection negligible latency.

N/A Battery
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What it is: The power source of your headphones. All headphones with active features have a battery that will deplete over time.
When it matters: To continue using the active features of your headphones. Some models lose features or switch off completely when the battery is drained, which limits what you can do with them until the next charge.
Score components:
Battery Type
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What it is: The type of battery that the headphones use. Usually AAA or embedded, Li-ion rechargeable batteries.
When it matters: When your headphones run out of power. Rechargeable batteries usually charge via the headphones Micro-USB port whereas AAA batteries have to be replaced or charged with an external device.
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N/A
Battery Life
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What it is: The amount of time it takes for a headphones' battery to be completely drained. Battery life will vary depending on the active features used and volume level.
When it matters: For active headphones that connect wirelessly, have noise cancellation or other audio-enhancing features, that cease to work once the battery is dead.
Good value: >10hrs
Noticeable difference: 0.5hrs
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N/A
Charge Time
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What it is: The amount of time your active headphones have to be connected to a power source to charge from 0 to a 100%. However, charging time will vary depending on your power source.
When it matters: To be able to use the active features of your headphones. Especially, wireless ones that completely switch off and need to be recharged when the battery is dead.
Good value: 2h or less
Noticeable difference: 0.25h
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N/A
Auto-off
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What it is: A feature that turns off the headphones, after a set time, when they're not in use.
When it matters: To prolong battery life when the headphones are not being used, or if you forget to manually turn off your headphones.
:
N/A
Audio while charging
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What it is: Some active headphones remain usable while charging. They continue to stream audio and do not disable other active features.
When it matters: This makes sure that your headphones's battery are not being drained when your relatively close to a power source. However, this means wireless headphones will need a wired connection to the power source during the charging process.
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N/A
Passive Playback
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What it is: Active headphones that still work when all their active features are turned off or out of power.
When it matters: If you run out of power and do not have spare AA/AAA batteries or access to a power source to recharge your headphones.
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N/A

0 App Support
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What it is: The additional app provided to enhance your listening experience. They typically deliver a set of practical features that give you more control over the sound, noise cancelling and effects that the headphones produce.
When it matters: An app with a lot of features allows you to customize your listening experience to suit your taste and preferences. For example, additions like an equalizer can give you more bass or treble and room effects can simulate a bigger Soundstage in closed back headphones.
Score components: Subjectively assigned
App Name : N/A
iOS : N/A
Android : N/A
Mac OS : N/A
Windows : N/A
Equalizer
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What it is: Parametric, graphic or preset sound profiles that slightly alter the frequency response.
When it matters: If you want to tailor, your listening experience. Depending on what you're listening to you may want more or less bass for some tracks or more mid-range for vocals-heavy audio.
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N/A
ANC control
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What it is: Control over the Active noise canceling technology. This could be either a simple on/off button, and adjustable slider or even adaptive self-regulating noise cancellation.
When it matters: If you're in an environment where you need to monitor your surroundings or completely isolate yourself from ambient noise.
:
N/A
Mic Control : N/A
Room effects
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What it is: Room effects that enhance the audio quality to make it more immersive.
When it matters: If you want to further tweak your listening experience. Adding room effects, can simulate a more spacious Soundstage or deliver a surround sound-like feel.
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N/A
Playback control
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What it is: An in-app player that gives you access to play/stop, track skipping or volume controls directly with the app.
When it matters: It's a shortcut that allows you to control your audio without leaving the application.
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N/A
Button Mapping : N/A
Surround Sound : N/A

No compatible app.

In the box

Superlux HD 681 EVO In the box Picture

  • Superlux HD681 EVO Headphones
  • 1/8" to 1/4" Adapter
  • Carrying pouch
  • Audio Cables (x2)
  • Manual

Conclusion
SEE PRICE
Amazon.com

5.9Mixed Usage
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What it is This is the combination of the different use cases to evaluate how versatile the headphones are. Therefore an everyday headphone should be well-rounded enough to adapt to most situations and environments without significant losses in sound quality, design ergonomics or isolation.
Score components:
The Superlux HD 681 EVO are budget critical listening headphones that won't be versatile enough for all use cases. They sound surprisingly good for their price, and they're comfortable enough to wear for extended listening sessions without any fatigue. Unfortunately, they're bulky, cumbersome headphones that are not portable or stable enough for sports. They also barely isolate so they won't be ideal for commuting or to use in loud environments.
7.5Critical Listening
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What it is The level of audio fidelity a headphone can reproduce. Therefore a balanced and true representation of bass, mids, treble, soundstage and imaging, as well as a comfortable listening experience, is essential for critical listening.
Score components:
The Superlux HD 681 EVO like the HD 681 are a good and budget option for critical listening. They deliver a slightly more powerful bass than the HD 681. They also do well reproducing instruments and vocals that aren't overshadowed by the stronger bass. However, although semi-open they do not have the most spacious soundstage and their bass varies a bit due to positioning. This makes them slightly inconsistent but overall their sound quality is good enough even for more critical listeners.
5.2Commute/Travel
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What it is How well the headphones handle the loud environments involved in commuting or traveling. Therefore your listening experience should be comfortable, hassle-free and as isolated from noise as possible.
Poor for commuting. They're not made for this use case. They have a semi-open design that doesn't block a lot of ambient noise and they're a bit of hassle to carry around on your person without a bag.
5.4Sports/Fitness
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What it is How well-adapted the headphones are, to use while doing sports or strenuous exercise. Therefore the headphones should not be too cumbersome and deliver a stable and comfortable listening experience.
Not made for sports. They're bulky and impractical to use outdoors. They're a bit more comfortable than the HD 668B but they're less stable and won't be ideal to use while doing physical activities. They also they don't have any controls, which makes controlling your music source while exercising a bit more of a hassle.
5.5Office
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What it is How well the headphones can deliver a comfortable and isolated listening experience in an office-like environment. They should not leak much and should block the noise of a busy office.
Score components:
Subpar for office use. They let a lot of noise seep into your audio and also leak a lot which might be distracting to your colleagues.
Average for home theater use. They have a good audio reproduction and no latency since they're wired. They're a suitable option to watch movies especially on a tablet or PC since the length of the cable won't be an issue. However, for a home theater set up, you will most likely need an aux extension cord.
Below average for gaming. They have a good sound an comfortable design. they also wired so they have no latency. However, they also have no mic so they won't be ideal for gaming especially for multiplayer games online.
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