I (ab-)use this topic to short-review any headphone I have formed a (subjective) opinion about. If not mentioned otherwise, I own them. But I also included headphones which I do not own and I just spent some time with. So, some of these are just "first impressions".
Headphones:
In Use:
AKG K371 (My last purchase. I bought them after trying them out in a Hi-Fi store. Great comfort and timbre to my ears. I wear glasses, so I likely hear them slightly less bassy than measurements imply. I hear some slight peaks and dips on the tone generator in the treble, but somehow I dont mind them much.)
AKG K702 (It lacks bass by default, and I often have to reposition them on my head when using the stock pads. Stock pads + the right EQ sound quite great though, very open and spacious. The 712 pads fit my head way better. I'd like to find a good EQ preset for the AKG 702 with 712 pads.)
Rode NTH-100(M) (I mostly use the headset version for my work. The cooling pads are very helpful, but it is a bit heavy on the head. Very smooth sound signature. A bit boring in stock, but great with Oratory1990s EQ. Measurements imply rather high distortion, but people overestimate how noticeable this is on normal volume. They always sound closed-in though.)
Sennheiser HD 560S with
@solderdude filter (The head band is slightly uncomfortable, and the filter turned out to filter a bit too much in the 6-8k region for my taste. I could EQ that but I ended up using other headphones most of the time.)
Sennheiser HD 600 (Bought them after the 560s when Sennheiser sold them refurbished for 219 Euro. I exchanged the headband for the Dekoni for better comfort. The build quality is great. Sound-wise I expected even more on a "technical level" as they are praised so much. Good macro-tonality, but closed in and actually even slightly peaky in my ears. I did not find the perfect EQ settings for them yet. Unit variation seems to be rather high.)
Sony MDR-M1ST (An on-ear headphone I bought used online out of a whim. I shouldnt have done that. Very light, stylish, sturdy build quality, not too comfortable though. Sounds fine with EQ.)
Used to own / Not in use / Listened to them elsewhere:
Hifiman Deva Pro (I recently had an accident with them, now the headband is a little deformed. Maybe I can fix them somehow. I like the comfort and the fact that I they are an open-back Bluetooth headphone. They sound very open. Hard to EQ because of resonances in the treble. I still think they offer a lot for the price. They are for nerds who are willing to invest some time into EQing.)
Beyerdynamic DT 880 32 Ohm (Gave them away to a friend. Sometimes I regret that. It sounded great with EQ. Even without EQ it did not sound as peaky in my ears as some people said. A bit intimate though, with and without EQ. Rather comfortable, even though the round pad shape did not to fully sorround my ears.)
Denon AH-D9200 (A friend owns these, and I was able to spend a few hours with it. They are not neutral, but I think they have a super fun warm U-Shaped sound signature. They cost too much though. High build quality, which should be expected for the price.)
Sennheiser HD490 Pro (I listened to it in a hi-fi store with my own music for ~15 Minutes. I would recommend these to most people. Slightly smoothed neutral. Somehow I perceived them as just as clear as my HD 600. Potential "endgame" if you are not crazy like many of us. Personally I did not like the style of the headband, but most people will likely love the comfort.)
Neumann NDH-30 (I listened to it in a hi-fi store with my own music for ~20 Minutes. Impressive bass and soundstage. Also a good comfort for my specific head shape. The HD490 is a safer choice though. The treble changed a bit depending on how you wear them. This seems to be a typical "big round ear cup"-problem, as I perceived the same with my AKG 702.)
Beyerdynamic DT 700 Pro X/900 Pro X (I listened to both in a hi-fi store with my own music for ~5 minutes each. I found them less comfortable than the old Beyers. Sound-wise they were better. The 700 Pro X was especially good for a closed-back. Neither of them sounded sharp in the treble on first impression.)
Austrian Audio X60/65 (I listened to both in a hi-fi store with my own music for ~5 minutes each. Good comfort, but peaky in the treble to my ears. I quickly ended up prefering and buying the cheaper & similarly-designed AKG K371.)
Superlux HD 660 Pro 150 Ohm (These can sound surprisingly good with EQ. I had to put in some work though, most measurements did not suit my experience. They are a bit damaged though so they usually stay in my closet.)
Sennheiser HD 555 (My first "serious" headphone as a kid. By the time I thought it was the best thing ever, but it probably wasn't. Broke a long time ago. I might buy it again someday out of curiosity.)
Teufel Aureol Massive (Horrible headphone. Too much bass which bleeded into the mids.)
Teufel Aureol Real (I hardly remember, but I think it was a quite good and comfortable open-back. The pads wore out and I didnt find adequate new ones. Sound Profile: Neutral with boring bass.)
Teufel Aureol Real Pure (Gave it away to a friend. Actually very different from the "non-pure". Closed Back, very different build, bassy V-Shape.)
IEMs (I dont EQ IEMs.):
In Use:
Etymotic ER4XR (Bought them used online. I mainly use them for travelling. The tonality works great for me for most tracks. I especially like them with classical music. I am going to check out the ER2XR as well.)
Letshouer Cadenza 4 (I hoped to find my "end game" IEM with these. But they ended up being another shape of "fine, but not perfect". A bit too thin. Upper Treble is impressive with the right ear tips.)
Truthear Zero RED (Relaxing tonality, great for pop and old rock music. The amount of bass is just perfect for my taste. A bit boring though.)
Tripowin x HBB Olina SE (Bought them used online. My "upgrade" over the 7hz Salnotes Zero - a bit less bright but still just as clear. Perfect "fun" tonality to my taste. I think a lot of people would love these.)
CCA Trio (Similar and better than the KZ D-Fi. Very "impressive" sounding, bassy and analytical at the same time. Great for electronic music. A well-rounded tonality overall, not shouty.)
Truthear Gate (Bought them because they are cheap and the FR should be right up my alley. It seriously lacks treble extension though.)
Moondrop Space Travel (Amazing offer for the price; a good christmas present for a friend. It is hard to get a good seal, otherwise good tonality.)
Used to own / Not in use:
7hz Salnotes Zero (Gave it away to a friend recently. Very good tonality for the price. Slightly harsh in the treble.)
KZ D-Fi (Gave it away to a friend recently. Lacks a bit 500hz region and presence range, but it is pretty good. The shell looks great but is a bit clunky.)
Shure SE 215 (My first "serious" in-ear. Used them for like 10 years. I lost the first one, the second one was stolen. I can hardly compare them by now but by the time I thought they were good. I think they lacked clarity in retrospect.)
Tin T2 (I bought them after the SE 215. I remember them to be better than the Shure sound-wise, but I dont use them anymore. No subbass. The AutoEQ/Oratory1990 EQ profiles sound off to me.)
Tin T2 DLC (Gave it away to a friend recently. Same shells as the T2. Most people will prefer these. A bit shouty.)