Superlux HD 668B Headphones Review

Reviewed May 26, 2017 at 11:36 am
Superlux HD 668B Picture
Usage Ratings - Version 1.3.1
5.5
Mixed Usage
8.1
Neutral Sound
4.5
Commute/Travel
5.3
Sports/Fitness
5.3
Office
4.4
Wireless Gaming
6.2
Wired Gaming
1.8
Phone Call
Type Over-ear
Enclosure Semi-Open
Wireless No
Noise Cancelling No
Mic No
Transducer Dynamic

The Superlux HD 668B are great-sounding and affordable critical listening headphones. They let in a lot of ambient noise and leak enough to be distracting to those around you, so they won't perform as well for other use cases. They're also a bit bulky and cumbersome to carry around. However, when it comes to sound, they deliver an almost unmatched audio reproduction at this price range.

Our Verdict

5.5 Mixed Usage

Below-average for mixed usage. These headphones are for critical listening and aren't designed to be versatile in all environments. They won't block a lot of noise for your commutes, and they're too leaky to take to the office. They're also a bit bulky and cumbersome for sports, but they're an excellent-sounding and affordable pair of headphones for critical listening.

8.1 Neutral Sound

The Superlux HD 668B are a good, budget option for neutral listening. They deliver a satisfying and tight bass that doesn't overpower the presence of instruments and vocals. They have a relatively flat mid-range but a slight bump in the high-mid /low-treble that makes them sound a bit sharp on some tracks especially with songs that are already a little bright. Sadly, they don't have a soundstage as immersive as some of the other fully open-back headphones, but overall the sound quality of the HD668 is sufficiently good for both casual and neutral listeners.

See our Neutral Sound recommendations
4.5 Commute/Travel

Subpar for commuting. They're not intended for this use case as they don't block a lot of ambient noise, they're not portable and do not have the most durable build quality.

See our Commute/Travel recommendations
5.3 Sports/Fitness

Not made for sports. They're bulky and impractical to use outdoors. They're also not stable enough to use while doing physical activities and will slide off your ears if used while running or working out. Also, they don't have any controls, which makes controlling your music source while exercising a bit more difficult.

See our Sports/Fitness recommendations
5.3 Office

Below-average 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.

See our Office recommendations
6.2 Wired Gaming
1.8 Phone Call
  • 5.5 Mixed Usage
  • 8.1 Neutral Sound
  • 4.5 Commute/Travel
  • 5.3 Sports/Fitness
  • 5.3 Office
  • 4.4 Wireless Gaming
  • 6.2 Wired Gaming
  • 1.8 Phone Call
Pros
  • Great sound quality.
  • Lightweight design.
Cons
  • Sensitive to noisy environments, by design.
  • Plasticky build quality.
  • Uncomfortably tight for some listeners.
  1. Update 11/21/2019: Converted to Test Bench 1.3.1.
  2. Update 11/6/2019: Converted to Test Bench 1.3.
  3. Update 2/16/2018: Converted to Test Bench 1.2.
  4. Update 8/10/2017: Converted to Test Bench 1.1. Learn more about our new versioned test bench system here.

Check Price

Test Results

Design
Design
Style

The HD 668B look very similar to the AKG K240. They have paddles instead of a fabric strap to cushion the headband and an odd-looking male audio jack in place of a more traditional female port for the detachable cable. However, the rest of the HD 668's design, including the large semi-open ear cups, look like a cheaper version of the K240s. Overall, they have an understated and utilitarian appeal but they're not headphones you would use outdoors for their style.

6.0
Design
Comfort
Weight 0.51 lbs
Clamping Force
1.2 lbs

The Superlux HD 668 are decently well-padded but a bit too tight on the head. They're lightweight and the ear cups are large and fit well around most listeners ears. Unfortunately, the headband doesn't extend to accommodate different head sizes, so they tend to feel a bit tight. That and the paddles that act as a cushion for the headband put quite a bit of pressure, which will get fatiguing after a long listening session.

0
Design
Controls
OS Compatibility
Not OS specific
Ease Of Use N/A
Feedback N/A
Call/Music Control No
Volume Control No
Microphone Control N/A
Channel Mixing
N/A
Noise Cancelling Control N/A
Talk-Through
N/A
Additional Buttons N/A
6.8
Design
Breathability
Avg.Temp.Difference 4.8 C
5.2
Design
Portability
L 9 "
W 7.1 "
H 4.1 "
Volume 262 Cu. Inches
Transmitter Required N/A

The Superlux are lightweight but too bulky and cumbersome to be portable. The ear cups do not fold or lay flat, so unless you have a bag, they will be a hassle to carry around on your person.

5.5
Design
Case
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.

5.5
Design
Build Quality

The Superlux HD 668 are cheaply made and plasticky. They feel like a budget version of the AKG K240, which shows in their build quality. They have a plastic design with no metal parts, and all the materials used in their build quality feel slightly low grade. They won't break if they accidentally fall once or twice, but they don't feel like durable headphones. The paddles, especially, are weak points that will wear over time.

6.5
Design
Stability

The HD 668B are tight on the head which make them decently stable. They won't fall during casual listening sessions and may even be tight enough for a light jog but they are not sports headphones. The earcups are a bit bulky and move a lot under physical activity so they won't be the ideal headphones to go running with. On the upside, the detachable audio cable will disconnect if it gets hook on anything

Design
Headshots 1
Design
Headshots 2
Design
Top
Design
In The Box

  • Superlux HD 668B Headphones
  • 1/8" to 1/4" Adapter
  • Audio cable (x2)
  • Carrying pouch
  • Manual

Sound
Sound
Sound Profile
Bass Amount
-2.16 db
Treble Amount
1.27 db
7.5
Sound
Frequency Response Consistency
Avg. Std. Deviation
0.49 dB

Good consistency. The Bass Range of our Over-Ear and On-Ear headphones are measured on 5 different human subjects, 5 times each. In the graphs, each line represents an individual's average Bass response. The variance in the Bass range is very little, except for one of our test subjects who wears glasses, which gets about 3dB less Bass at 40Hz. In the Treble Range the variance is about +/-3dB is which is decent.

Sound
Raw Frequency Response
8.6
Sound
Bass Accuracy
Std. Err.
1.89 dB
Low-Frequency Extension
33.15 Hz
Low-Bass
-3.09 dB
Mid-Bass
1.49 dB
High-Bass
0.82 dB

Very good Bass Range performance. Low-bass which is responsible for low-end thump and rumble is slightly lacking, but the rest of the Range is virtually flawless.

9.0
Sound
Mid Accuracy
Std. Err.
1.38 dB
Low-Mid
0.03 dB
Mid-Mid
-1.31 dB
High-Mid
-0.77 dB

Excellent Mid-Range performance. Low-mid is reproduced flawlessly. There is a small but broad dip surrounding 1KHz, which tends to push vocals/leads to the back of the mix. However, at about 1dB this effect will be very subtle.

7.8
Sound
Treble Accuracy
Std. Err.
3.64 dB
Low-Treble
-0.68 dB
Mid-Treble
3.48 dB
High-Treble
2.09 dB

Good Treble Range performance. Low-treble and treble are a bit inconsistent. Additionally, treble and high-treble are overemphasized by a couple of dBs, making these headphones a bit bright and sharp on certain tracks.

7.1
Sound
Peaks/Dips
Peaks
1.87 db
Dips
1.37 db
8.4
Sound
Imaging
Weighted Group Delay
0.33
Weighted Amplitude Mismatch
0.31
Weighted Frequency Mismatch
1.78
Weighted Phase Mismatch
10.12
7.7
Sound
Soundstage
PRTF Accuracy (Std. Dev.)
1.64 dB
PRTF Size (Avg.)
7.04 dB
PRTF Distance
11.79 dB
Openness
9.2
Acoustic Space Excitation
6.6
8.0
Sound
Weighted Harmonic Distortion
WHD @ 90
0.100
WHD @ 100
0.189
Isolation
2.5
Isolation
Noise Isolation
Isolation Audio
Overall Attenuation
-6.69 dB
Bass
0.16 dB
Mid
-0.23 dB
Treble
-19.73 dB

Poor Isolation. Given the semi-open design of these headphones, poor isolation is natural. These headphones don't block any noise below 1KHz. Above that, they achieve about 20dB of reduction which actually is above average.

4.5
Isolation
Leakage
Leakage Audio
Overall Leakage @ 1ft
51.95 dB

Poor Leakage performance. The semi-open HD 668B leak less than some fully open-back headphones, but more than the ones with a closed-back design. The significant portion of their leakage is between 400Hz and 10KHz which is a relatively broad range, and the overall level of the leakage is also fairly loud.

Microphone
Microphone
Microphone Style
Integrated
N/A
In-line
N/A
Boom
N/A
Detachable Boom
N/A
0
Microphone
Recording Quality
Recorded Speech
N/A
LFE
N/A
FR Std. Dev.
N/A
HFE
N/A
Weighted THD
N/A
Gain
N/A
0
Microphone
Noise Handling
Speech + Pink Noise N/A
Speech + Subway Noise N/A
SpNR
N/A
Active Features
N/A
Active Features
Battery
Battery Type
N/A
Continuous Battery Life
N/A
Additional Charges
N/A
Total Battery Life
N/A
Charge Time
N/A
Power Saving Feature
N/A
Audio While Charging
N/A
Passive Playback
N/A
Charging Port N/A
0
Active Features
App Support
App Name N/A
iOS N/A
Android N/A
macOS N/A
Windows N/A
Equalizer
N/A
ANC Control
N/A
Mic Control N/A
Room effects
N/A
Playback Control
N/A
Button Mapping N/A
Surround Sound N/A

No compatible app

Connectivity
0
Connectivity
Bluetooth
Bluetooth Version
N/A
Multi-Device Pairing
N/A
NFC Pairing
N/A
Line of Sight Range
N/A
Default Latency
N/A
aptX Latency
N/A
aptX(LL) Latency
N/A
0
Connectivity
Non-Bluetooth Wireless
Non-BT Line of Sight Range
N/A
Non-BT Latency
N/A
10
Connectivity
Wired
Analog Audio
Yes
USB Audio
Yes
Detachable Yes
Length 10 ft
Connection 1/8" TRS
Wired Latency
0 ms
Connectivity
PC / PS4 Compatibility
PC / PS4 Analog
Audio Only
PC / PS4 Wired USB
No
PC / PS4 Non-BT Wireless
No
Connectivity
Xbox One Compatibility
Xbox One Analog
Audio Only
Xbox One Wired USB
No
Xbox One Wireless
No
0
Connectivity
Base/Dock
Type
N/A
USB Input
N/A
Line In
N/A
Line Out
N/A
Optical Input
N/A
RCA Input
N/A
Dock Charging
N/A
Power Supply
N/A

Superlux HD 668B Price

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