It's been a while since I did this, and some headphones have come and gone, so I figure it's worth ranking them again.
1a. Hifiman HE-500 - My go-to for general music listening. Not a single weakness, and basically everything they do is incredible; large soundstage, smooth highs, slightly boosted, clean bass, and flat mid range. Eventually I'll start looking for a headphone to top this, but I suspect I'm going to be looking in the $2000+ range.
1. Hifiman HE-500: Also my go-to can for general music listening and my opinion of them does not deviate too much from the above other than to add speed and creamy mids to its list of attributes. Furthermore, the HE500 simply presents its sound in an exciting and pleasing manner to my ears. I am probably one of the few who finds the original headband comfy. I also started looking for a headphone to top this and auditioned the LCD-2F, LCD-4, and the Utopia side-by-side with my HE500 at the SourceAV (same amp, balanced connections). I wasn't impressed with the LCD-4's, the Utopia had better layering, and the LCD-2F bass reached deeper than every can I tried that afternoon but (to my ears) its bass is less tight than the HE500 which makes it sound like it is enveloping some of the mids and treble (just my opinion). Among the three cans I auditioned, I would rate the Utopia as the best, the LCD-2F as different (but worth considering a buy), and the LCD-4 as my least favorite. However, the HE500 can still trade punches with the Utopia, which is why I felt that the price differential between the Utopia and HE500 did not even remotely reflect the difference in sound quality between the two.
2. Sennheiser HD6XX: The king of the mids in my collection imo. My first hi-fi can. Initially, I was disappointed with its bass response but soon picked up on microdetails that I never heard before in familiar songs. Thereafter, I was addicted. Currently, I use a modded Darkvoice 336SE OTL amp to drive these cans, which is a match made in heaven. On my THX AAA 789 (balanced), the cans still retain their smooth character but they are a bit too smooth and boring when compared to its Darkvoice pairing and the HE500's.
3. AKG K501: Classical king. Yes, there's bass roll-off, and its 120ohm impedance makes it less ideal for my Darkvoice OTL amp (70-160ohm output impedance according to ASR). However, its mids and treble are spot-on for classical (the latter with sufficient air), and its soundstage makes me feel like I'm sitting in a concert hall. I still have to re-cable my pair and see whether extra juice from the THX AAA 789 balanced output would be beneficial to this can. SE is fine for these cans, but I feel that I haven't reached their potential yet.
4. Sennheiser PX-100 (v.1): My first headphone apart from whatever came stock with any audioplayer. Bass is pretty thick, the mids are fairly nice and the treble has enough presence to make these my goto cans for over 10 years, as their sound signature is enjoyable and the listening experience effortless for all music genres despite being less resolving than the other cans perched above it. Also, they're so lightweight and comfortable that I hardly notice that they're on. To this day, I still use them for gaming, movie watching, YT, and any non-critical listening. I stayed true to the original PX-100's (v.1), as the later product updates failed to woo me away from the originals.
5. Koss PortaPros: Competitor to the PX-100, but definitely more v-shaped and more bass quantity than the Sennheisers. Great for edm, some pop, and not much else since I like my mids.
6. Monoprice Modern Retros: Like strapping subwoofers to your head. Good for rap, edm, techno, dnb, and any bass-heavy tune. However, for any other genre, the above is better imo.
7. Sennheiser HD414X (2000ohm): Historical curio. Sibilant even when hooked up to my tube amp. Virtually no low end. But hey, at least it is comfortable.
8. M&J GL2: It's got wood but not much else in this dynamic/electret hybrid. Brainwavz pad swap helped the sound at the expense of comfort as the headphone is now directed downwards into the top of my skull, hello hotspot (or rather pain-spot). V-shaped and decent soundstage after the swap, but again not much else. It's now collecting dust on a yoga block.
9. 1More triple driver over-ears (graphene): If pain has a name, this one is it. The top of the headband creates a downward pressure on the top of my skull at a single point such that it seems that these cans are more interested in performing neurosurgery on me rather than offer any sound reproduction that is pleasant to my ears. Their sound is V-shaped and seem thin to me, the latter of which is due to the smallness of the pads that makes them essentially an on-ear can but without the construction or lateral inward pressure to produce the necessary seal. These will definitely be sold in the future.
Undecided. LCD2 rev. 1: I just got these this week for a good price. They are okay comfort-wise, as being a swimmer has the added benefit of strong neck and upperback muscles. I've worn these and the HE500 for hours (separately of course) without feeling fatigued. As for the sound, yes they're dark. However, I was surprised that the bass extends just slightly lower than the HE500's. Then again, I only received a SE cable with my purchase, and I have a spare ratty DIY L,R mini-XLR SE cable lying around that I can reterminate with a 4-XLR adapter. So, I'll be interested in hearing whether extra juice from the balanced output of the THX AAA 789 will improve things. Otherwise, the bass of the LCD2.1 has less distortion than the HE500 (e.g. intro of Bob Marley's Concrete Jungle), mids are nice (except there's other mids I prefer), and the treble is present. Nothing to rave about other than how the bass, mids, and treble seems to be cohesive but the overall sound is veiled.
