TLDR;
Comfortable, well enough built, decent isolation, easy to drive, sounds good as-is and great with EQ.
Build, Accessories and Comfort
Built entirely out of matte plastic and vinyl, the K371 doesn’t look or feel premium the way that my DT 1990 does. Even my HD58X feels a bit more premium with its glossy plastic and metal accents. Looks notwithstanding, the K371 has a pleasing heft without feeling heavy, and it does feel solidly made. The unique adjustment mechanism works well enough, though I’d like it to hold its size a bit better. The headband doesn’t cause any hotspotting and the pads are large and well padded enough to accomodate my ears without irritation. Clamping force seems just right.
The K371 has a single-sided headphone entry using a 3 pin Mini XLR connector. I’m used to this kind of connector from the DT 1990 and it’s probably my favorite. Being single sided keeps the cable away from my hands while working, the Mini XLR jack is more durable and secure than 2.5mm or 3.5mm connectors like on Hifiman but easier to plug/unplug than the connectors on my HD58X, and it’s easy to find affordable Mini XLR cables. Being only a single-sided 3 pin MiniXLR, it doesn’t allow for switching to balanced cables, which is no problem for me but something to be aware of.
The K371 ships with 3 cables, a short, a long and a coiled. The connectors on the cables seem sturdy and have adequate strain relief, and I appreciate the screw-on 1/4" adapters. The cables themselves do seem a bit thin and I worry about their durability. Thankfully they can be easily replaced if that becomes necessary.
Isolation
I haven’t heard a lot of closed back headphones. Before I got deep into headphones as a hobby I owned the Panasonic RP-HTX7-W1, but can’t remember much about how it sounded. Later I had the Sennheiser HD598Cs which I remember sounding better, but I rarely chose it over my open backs and it eventually got run over by a car. Compared with what I remember of those, the K371 isolates well. It doesn’t completely shut out the outside world the way that my Etymotic HF5s do, but it does a good job of blocking out people talking in the next room and makes it easy for me to listen at low volumes.
Amping
The K371 needs less power than my HD58X and DT 1990. The only bummer is that the low impedance doesn’t trigger the high output mode on my LG V20 so I have to trick it into doing that using something like this 80ohm impedance adapter.
Sound
In a nutshell, the K371 sounds good but not perfect, and it can be easily eq’d to sound great. For casual listening (movies, background music and such) I’m okay without EQ, but for focused listening I’d take an un-eq’d HD58X over this. With EQ, they’re both great.
Bass
Note - the K371 seems fairly sensitive to seal. I wear glasses and need to make sure to press on the ear cups after putting this headphone on to get a good seal. Thankfully it stays in place so I don’t have to keep my hands on the whole time I’m listening!
It seems like every closed back I’ve heard (especially the HD598Cs) has a scooped upper bass region that makes it sound hollow and echoey. The K371 doesn’t completely escape this fate, but it does better than the 598Cs for sure. It’s got very good sub-bass extension and I even find the sub-bass a little too much at times. It creates that sense of pressure that I get from something like the LCD2C but when combined with the hollowed out bass it sounds a bit artificial and detached. Daft’ Punks Get Luck and Rage’s Killing in the Name demonstrate what I’m talking about here–the bass lines create a lot of pressure and a little bit of punch, but they completely lack any of the fullness and warmth that I associate with those low frequencies. I think this is what people mean when they talk about “detached” bass.
Mids
The K371’s mids seem very well balanced. Listening to acoustic music like Joni Mitchell’s Little Green, the guitar and vocals are well balanced, clear and have a very natural timbre. They lack a bit of fullness because of the aforementioned issues in the upper bass, and the upper midrange can get a little shouty, which I can notice on female choral vocals like on R.I.A.S. Kammerchor’s Bach Motets and on trumpet like on Freddie Hubbard’s Red Clay, but especially at lower volumes this isn’t too bothersome.
Highs
The theme of good but not perfect continues in the treble. It’s well extended, fairly even handed and doesn’t exaggerate sibilance. Strings sound airy and cymbals sound realistic. If I were to nitpick, listening to something like Phronesis Eight Hours, cymbals sound a tad softer (splashier) than I like and piano sound a little less brilliant than I imagine it.
Imaging/Separation/Soundstage
The K371 sounds like headphones. As usual for me, crossfeed helps it sound a little more natural. Separation is good, even on busy stuff like Kleiber’s performance of Beehoven’s 5th. Some people say closed backs sound more claustrophobic than open backs. Compared to the HD58X and DT 1990, the K371 honestly sounds pretty similarly. My LCD2C sounds “bigger” but I think that’s mostly because it has much deeper pads.
Distortion/Volume Handing
I can turn the K371 up louder than I’m comfortable with and I don’t notice any grain or other problems that I do hear when cranking the volume on headphones like the HD58X.
EQ
I love to EQ. The K371 makes a great platform for EQ because the place it needs EQ the most is the bass, which also happens to be the easiest region measure and EQ. The mids and treble are pretty close to my idea of “right”, which is good because these can be tougher to tune.
Here’s what I’m running right now:
Low Shelf 40Hz Q1 -3.5dB - Brings the sub-bass pressure to a level that I consider more natural
Peak 65Hz Q2 +3dB - Fills in a dip in the bass to add some punch
Peak 153Hz Q3 +2dB - Fills in a hole in the upper bass to get rid of the hollowness
Peak 5900Hz Q5 +3dB - Brings up the low treble to add brilliance to piano and that “metal” sound to cymbals
(Optional) Peak 80Hz Q0.25 +2dB - Adds some warmth if you’re into a warmer sound. Works well in conjunction with crossfeed which tends to soften bass.
