Sennheiser HD 25  Headphones Review

The Sennheiser HD 25 are tuned with a loosely flat sound signature that somewhat exaggerates high-bass and low-mids with a blast of treble. You can use them for casual listening, and they work well for monitoring dance music, electro, vocal-centric, and other music genres. However, they roll off low-bass rumbles, so deep bass can sound relatively weak with a blast of high-treble emphasis.

The tuning makes sense for DJs, considering that hearing bass and rhythm are key to synchronizing tracks, as are vocals. With the peak halfway through the mid-treble, you won't miss out on any high-pitched subtleties that can inform tracking decisions, but it can sound relatively piercing.

If you're interested in tinkering with their sound, you can download a folder of EQ parameters and use it to tweak the headphones to match the target curves in our Graph Tool more closely.

These headphones have disappointing frequency response consistency. In our testing, people with larger heads tend to experience more inconsistent results in the bass range. The good news for people who wear glasses and have smaller heads is that the consistency isn't too bad.

You'll want to pay attention when you put them on so that the bass and treble regions don't vary between wears. In this regard, the ear cup, which you can pivot forward or backward to free your ear, can allow you to hear the room or someone who needs to chat in the middle of your DJ set without fully removing the headphones. This convenient feature can mitigate some instances where you'd have to remove the headphones and possibly hear an inconsistent frequency response between wears.

The bass target compliance of the Sennheiser HD 25 is okay. It tilts to emphasize the high-bass region yielding a boomy low-end but without a full depth and body. Particularly, the attack of bass instruments, like kick drums and plucked bass strings, gain a bit of added boominess. These don't sound overly rumbly with sub-bass parts like deep bass synth lines, though. For following a song's beat, the high-bass emphasis is useful.

These have excellent mid-range target compliance. A bump in the low-mids that continues from the bass can make busy songs with a lot of bass and mid-range parts sound slightly bloated, but it also thickens bass harmonics, which you may prefer on tracks like She's Lost Control by Joy Division. Throughout the rest of the mids, the sound is quite balanced, meaning that apart from the effects of bass exaggeration, which can slightly overwhelm voices, guitars, and synth pads, it sounds clear.

The treble target compliance is very good. For about two-thirds of the low-treble region, the frequency response follows a flat tuning and sounds like the highest notes of a guitar come across evenly. However, the dip through the low-treble and the mid-treble dulls the articulation and detail of vocals, for instance. The rest of the mid-treble has a prominent peak that can cause early fatigue with its piercing exaggeration of harmonics. However, that can also lend airiness to the top end of your audio, which you may enjoy.

The peaks and dips performance is good, so the headphones match their flat sound signature well for the most part. There are small dips and bumps, but they're relatively minor through the bass and mids. A peak in the low-treble can add a bit of a harsh edginess to vocals. The dip in the low-treble warms up sibilant sounds like S and T, which can sound a bit dull. Meanwhile, a significant peak in the upper-treble lends a piercing exaggeration to other high-pitched sibilants and instrument harmonics, which can prematurely cause your ears fatigue, if you have sensitive ears.

The headphones have very good stereo mismatch performance overall. The L/R drivers are well-matched in weighted amplitude and frequency response. Despite the mismatches in the low-bass and high-treble, these are within good tolerances for a stable stereo image. The weighted phase response exhibits mismatch in the high-treble. However, there isn't much audible musical content in those frequencies, and depending on your hearing's sensitivity to those frequencies, you may not notice it with real-world use. These results are true for our unit, but your pair may differ.

The Sennheiser HD 25's weighted group delay is decent. The bass sounds tight for the most part and the treble sounds transparent. Since these headphones considerably roll-off low-bass in the frequency response, the wobbles in the low-bass group delay isn't significant.

These headphones have terrible pinna-related-transfer-function (PRTF). Most closed-back headphones, by design, have this trait. This lack of interaction with your pinna suggests these do a poor job of mimicking an angled reference speaker.

The Sennheiser HD 25 have very good harmonic distortion. They can reproduce audio cleanly at both 94 and 104 dB/SPL.

These are sensitive headphones that don't need an amp to drive them. They're capable of getting loud, and if connected to a low-noise source, they don't add any noise to your audio. However, due to their sensitivity, they will noticeably amplify any noise in the signal chain if it's already present.

These are the settings used to test these headphones. Our results are only valid when used in this configuration.

The Sennheiser HD 25 headphones are lightweight on-ear headphones with closed backs. The housing and headband are plasticky with exposed, detachable cabling that runs through the right ear cup and along the headband to the left ear cup. They have faux-leather padding along the headband and ear pads—which you can replace. Otherwise, these are minimalist in design. One of their most unique features is the headband, which can split for greater fit adjustments. One of the few pops of color is the red cable to differentiate the right ear cup at a glance. You can flip the left ear cup forward or backward. Our unit is 'Black,' and other colors include 'Blue,' and the limited edition 'White.'

The Sennheiser HD 25 provide good comfort. They're very lightweight compared to other headphones popular with DJs and enthusiasts, and they don't clamp particularly hard, either. For on-ear headphones, they also feel comfortable for long stretches (even if you wear glasses), and despite the visually sparse padding along the headband, they don't add much pressure to the top of your head. You can also split the headband to distribute their weight better. Splitting the headband allows the headphones to stay in place better if you flip the ear cup and accommodate various head sizes. However, if you do wear glasses, flipping the ear cup forward can bump into your glasses. The downside of the headphones is that they warm up quickly, and on-ear headphones, by design, can only feel so comfortable because they apply pressure to your ears.

The Sennheiser HD 25 are middling headphones for portability. They're not particularly large, but they don't collapse down to a smaller footprint, and the ear cups can't rotate flat either. However, their narrow, straight cable and lightweight frame aren't bulky, but they definitely take up space in a bag. Because they don't get more compact, their portability is on par with collapsible over-ears like the Audio-Technica ATH-M50x. That said, if you're really trying to save space, you can fully remove the headband from the ear cups, but if you do that, you might want to get a third-party case or pouch to keep the loose parts together.

These headphones have alright build quality. While the lightweight frame and replaceable parts are positive build choices for the very practical design, they're also very plasticky, besides the metal hinge to pivot the left ear cup. The exposed cabling is useful for replacing the cable if the day comes that it breaks, but it also makes it more vulnerable to damage than if it were sealed into the housing. Our unit arrived out of the box with some slightly loose padding on the headband where it's glued to the headband's plastic. For slightly better build quality in a set of on-ears, the AIAIAI TMA-2 DJ feel more solid and are easier to repair and replace parts. However, you might miss the padded headband on the Sennheiser cans.

These headphones have good stability. Unlike most headphones, the headband splits so you can dial in not only their weight distribution but also create essentially a second point of contact for the headband to grip on your head. This accommodates different hairstyles and head shapes. You can keep them on with small movements and bobs. They can come loose and fall off if you get into your music and headbang. In all, that's normal for on-ear headphones.

• Sennheiser HD 25 headphones
• TRS audio cable (x1)
• 1/8" to 1/4" adapter

The Sennheiser HD 25 have poor noise isolation. On-ear designs generally struggle with passive isolation because they essentially make do with clamping force and muffling materials to seal in your ears, unlike in-ear headphones that fully seal your canal and over-ears that seal around the whole ear. These headphones reduce the loudness of high-pitched sounds, like clinking glasses and some ambient chatter in the mids. As with most passive headphones, they don't suppress bassy sounds whatsoever.

For instance, if you're a DJ, you'll still hear the thump and rumble of what you're playing in the room's speakers. While not the healthiest solution for your hearing, the headphones can get loud to combat poor isolation.

In common scenarios, their noise isolation is poor. Bright sounds like shrieking bus brakes and clatter in the office kitchen are muffled to a degree. However, lower-pitched sounds, like the low ambient din of an airplane cabin, remain untouched by the headphones' passive isolation.

The leakage performance is acceptable overall. A rather large section of high-mids and treble escapes, so folks nearby can hear the treble content of your music, including bright lead instruments, vocals, and cymbals if you're at the office. The sound is thin and bright without significant bass content.

How well others can hear your audio depends on your environment and how loud you set the volume. If you're a DJ, it won't matter because the room will be far louder than anything leaking from your headphones.

The headphones have incredible wired connectivity. You get a single 1/8" TRS cable. It fits into the headband, connects to the ear cups, and hangs down along the right side of the headphones. You can replace the cable if it ever breaks because it's detachable. However, you may have to hunt down the same cable from Sennheiser because it's an uncommon connection. Also in the box is a 1/4" male to 1/8" female adapter.

You can connect the headphones to your PC. The generous cable length won’t hamper your ability to plug into a PC tower on the floor, either. Given that these headphones have a 70-ohm impedance, you can drive them without an amp.

These headphones can connect to your PlayStation's controller via an analog connection but only support audio playback. If you want to talk with friends, you'll need a separate microphone or a gaming headset.

Plugging in the cable to your Xbox controller for audio-only works fine with these headphones. However, you'll need a separate microphone if you want to speak with your friends while gaming.