Superlux HD 681  Headphones Review

The Superlux HD 681 look very similar to the AKG K240 MKII, thanks to the double wire headband and ski-band headband design. Their ear cups are nearly identical to the Superlux HD 668B, with the same circular enclosure design, but have red detailing to help it stand out from other budget-friendly headphones on the market. However, due to their plasticky build, their red and black color scheme looks cheap.

These headphones fit comfortably and are even more comfortable than the Superlux HD 668B. They're just as lightweight but have a better headband design that extends further and doesn't feel as tight on the head. They also have large ear cups that fit well around most listeners' ears. Unfortunately, the ear cup padding feels a bit stiff and can cause a bit of uneven pressure. While the padding isn't particularly uncomfortable, it's noticeable after wearing them for a while.

These cans have fair breathability. Thanks to their semi-open-back design, they allow some airflow to circulate within the ear cup. While they won't cause you to sweat if you wear them for long periods, they're not as breathable as open-backs like the Philips SHP9500.

These headphones have a lightweight design but are still bulky and cumbersome. The ear cups don't fold or lay flat, making them difficult to carry around if you don't have a bag.

They come with a somewhat rugged pouch that'll shield them from scratches, minor water exposure, and dust. However, it won't protect them against drops and impacts.

These cans have a disappointing build quality, though it's to be expected from at this price point. Like the Superlux HD 668B, they're made of low-grade plastic with no metal components and even feel like a cheaper version of the AKG K240 MKII. They won't break if you accidentally drop them once or twice. However, they don't feel like durable headphones.

These cans aren't as tight on the head as the Superlux HD 668B and are slightly less stable. It won't be a problem if you're listening to audio at your desk, but if you like to bop your head to the music, the ear cups can change in positioning. The audio cable isn't detachable either, so if it gets snagged on something, the headphones will be pulled from your head.

• Superlux HD 681 headphones
• 1/8" to 1/4" adapter
• Carrying pouch
• Manual

These cans have a neutral sound with bright sibilants. Even though they're semi-open-back headphones, they can reproduce a lot of low-bass, ensuring that tracks get adequate thump, rumble, and boom. Vocals and instruments also sound clear, natural, and accurate. Sibilants like cymbals are piercing, though.

If you'd like to tame the treble, boost the bass, or otherwise bring the frequency response of these headphones into line with one of the target curves shown on our Graph Tool, this downloadable folder of EQ presets will help.

These headphones have good consistency performance. If you have thick hair or wear glasses, you may notice a drop in bass, as these features can disrupt the ear cups' seal on your head. However, once you achieve a good fit, you'll experience more consistent audio delivery.

These headphones do a decent job of complying with our bass range target. The response is underemphasized across the entire range, though it's tilted in such a way that the low-bass is particularly lacking. As a result, there's not much in the way of bass-range rumble, though this is to be expected from semi-open-back headphones.

These cans have excellent mid-range compliance with our target curve. The response is pretty flat and neutral, so vocals and instruments are present, natural, and detailed in mixes. In songs like My Sharona by The Knack, male vocalists sound detailed and clear throughout the track.

The Superlux HD 681 have fair treble compliance with our target. A dip in the low-treble weakens the upper harmonics of vocals and lead instruments. However, the mid-treble is much more overemphasized, and sibilants like cymbals are piercing. In songs like Stairway to Heaven by Led Zeppelin, the electric guitar is overpowered by piercing snares, which are overly present in the track.

The peaks and dips performance of these headphones is good. The peaks and dips are fairly minor in the bass and mid ranges, with a dip in the mid-mid nudging vocals and instruments to the back of the mix. However, there's a peak between the high-mid to low-treble, making vocals and instruments sound harsh. A dip in the low-treble affects both drivers and removes some of the harmonic richness from vocals and lead instruments. However, the peaks in the mid-treble make sibilants, like hi-hats, sound piercing.

The imaging performance of these headphones is great. Even though we haven't tested very many Superlux headphones, those we have tested display solid imaging, which is an indicator of ergonomics and quality control. Imaging varies between units, though. That said, our unit's L/R drivers are well-matched in group delay, amplitude, frequency, and phase response, ensuring the accurate localization of sound objects like instruments in the stereo image. Peaks in the phase's response's high-treble range aren't audio with real-life content either, especially since they affect narrow frequency bands, and we lose sensitivity to this range over time.

The passive soundstage performance of these cans is very good. Their semi-open-back design allows them to create a wide, open, and natural soundstage that's more immersive than the Superlux HD 681 EVO.

The weighted harmonic distortion performance is good. At normal volumes, you'll experience clean and pure audio reproduction. However, if you push these cans to a high volume, there's some distortion present in the high-bass to low-mid range. It's hard to hear with real-life content, though.

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

The Superlux HD 681 have bad full-range noise isolation by design. They're not meant to block out background noise as they have a semi-open-back design, so if you're using them near an open window with traffic outside or next to people talking, you'll hear everything. They attenuate slightly better against treble range noises, but these sounds will still be audible.

These headphones have a poor noise isolation performance in common scenarios. They provide very little attenuation regardless of the situation, whether it's an aircraft cabin, busy street, or office environment. Their design will slightly muffle the treble range of external noise, but there's practically no attenuation against bass and mid-range frequencies.

These headphones are meant to leak audio by design to create a more immersive audio experience. Even at regular volumes, people around you will hear your audio.

These headphones have a non-detachable 1/8" TRS cable. Their latency via this connection type is very low, so you won't experience any sync issues between your audio and video.

You can connect these headphones to your PC via analog, but you'll only receive audio. They don't have a mic.

These headphones only support audio via analog if you plug their TRS cable into your controller's AUX port. They don't have a mic, though.

You can only receive audio via analog on Xbox consoles, as these headphones don't have a mic.