The HD681 will not put a lot of strain to your neck and head, even for long periods. Coming in at around 220 g, they are relatively light. This is due to the use of plastic as the primary build material, along with small metal tubes on the headband frame instead of large plastic or metal parts.
These headphones have what is called a V-shaped sound signature where the bass and treble is boosted while the mids take a backseat. The bass is powerful, deep and satisfying. Listening to bass heavy music will certainly be a good experience. The boosted treble makes audio detail up front, so nuances in the music can be clearly heard.
While the bass benefits greatly from the V-shaped sound signature, the highs are boosted by quite a lot, and can make the treble sound too harsh for some. Cymbal hits for example can be too washy and near distorted and can be fatiguing.
The ear pads are made of cheap feeling synthetic leather which can get warm rather quickly. To potentially add more discomfort, the cushioning inside these ear pads is quite thin, and can hurt the area around your ears when worn for many hours straight.
Despite the compact size. the bass is full, has great impact, deep extension yet is not loose. The low end also has a natural quality to it that makes these headphones great for music that is performed using real instruments.
The mids are slightly recessed, but also have a natural tone. The highs are the most recessed or rolled-off, but the detail and airiness of the music is not totally absent. This quality helps give the sound a smooth and pleasing tonality.
The K81 can be used “DJ style”, wherein only one ear cup is in contact with the head. The cups have a smooth swivel action so they can be rotated to face outwards. A user can choose to hold one ear cup up to his or her ear while flipping switches or turning knobs on the mix board with the other hand.
While these are already quite compact, the ear cups can be folded into the headband to reduce their size even further. This makes them easy to stuff inside a bag and travel with.
The clamping force is not too much at all, so acceptable levels of pressure will be applied on the ears. Also, the ear pads are thick with ample pleather padding on the surface. This combination provides adequate cushioning between the ear cups and sides of the head.
The aluminum headband itself has some good flex. Combined with the sliding mechanism of the ear cups, K81 can be adjusted to fit a wide range of head sizes. Also notable are the numbered steps on each side of the headband, which allow for accurate and consistent ear cup positioning.
Although it's mostly made of plastic, the materials don't feel cheap at all. Aside from feeling sturdy, the plastics have a smooth rubber coating which makes them feel premium to the touch. Also, the headband is made out of aluminum which is significantly more durable than an all plastic one.
While the ear pads are thick and give a lot of cushioning, some may still find this to be uncomfortable. Being on-ear, some pressure is applied onto the ears.Those who are sensitive to this may still feel some discomfort, especially when worn for several hours straight.
The cable is 2.5m which is fairly long. Since it is not detachable and the cable tends to tangle quite easily, it may cause some problems with regular home use or when taking these headphones on the go.
As expected of their price, these headphones are not able to deliver a lot of detail, clarity or accuracy in terms of the sound but they're still quite fun to listen to. There is a slight accentuation on the bass which gives it oomph and presence but is not overpowering. Mids on these headphones are recessed, but are still able to present a good rendering of vocals and guitars. The highs are not very detailed, which means that you will miss some of the more intricate sounds from the music, but they are good enough that the overall sound does not come off as too muddy.
Although it's made entirely of plastic, it does not feel cheap at all. The plastics used are of good quality. They can take a significant amount of flex with no signs of breaking.
With the closed back design, very minimal sound can seep into your music. Likewise, sound leakage is kept to a minimum so you won't be disturbing others near you with your music.
The ear cups are attached to a fixed head band, with a ball socket as the connection. Users then move the ear cups up and down the stationary head band. Available adjustment is quite limited though, so these headphones may not be suitable for individuals with bigger sized heads.
Despite being labeled as over-ear headphones, the cups are actually quite small. If you have larger ears, it is possible that these will fit a little too tightly, if not rest on your ears completely, which you may find uncomfortable.
The cable is around 10 feet long. While this can be a good thing for certain uses, the long cable can get tangled up pretty easily and can get quite difficult to manage if you decide to take these on the go. The included cable organizer can help mitigate the problem, but some might find it fiddly to use.
These press down on the head pretty tight, which some might find uncomfortable. With regular use and some stretching of the headband however, it is possible that the clamping force will loosen up over time, resulting in a much more comfortable fit.