About the HD265: I don't know what head-fi-ers are smoking when they diss the HD265. I think probably since most headphones have very warped frequency response (almost nothing as linear as the HD265), I think they probably believe what they are used to is 'good', whereas the truth of the matter is they have become accustomed to a very bright and highly warped sound (with lack of sub bass) which is found on virtually every other headphone on the market. They are probably worsening the situation with non-linear amps and EQ (to make those warped headphones sound a little better at the bottom), or they have never actually heard sub bass on a headphone before. So when they hook up a good pair of neutral headphone like the HD265 (very flat frequency response), it sounds 'wrong' to them. It's pretty funny actually. This is exactly how I feel when I hook up those tinny ridiculously overpriced headphones that are thin, sizzling, with no bottom. I need a flat response across all audible frequencies, not coloring the sound or missing frequencies. Why pay so much for a headphone that can't even reproduce the lower frequencies? Wouldn't you want at least all the frequencies of human hearing? Why settle for headphones with a big missing gap in the spectrum?
Eagle_Driver and Nak Man talk about bass hammering or muddy, bloated bass. That's probably what happens when you're overdriving the sub bass frequencies because the headphones you're used to (with that so-called 'tight, musical' bass), are actually incapable of rendering frequencies below 20-50 Hz properly (they are maybe 50dB too low on the frequency response at the low end). Once you have a headphone capable of rendering those frequencies at the correct level relative to the rest of the spectrum, if your setup isn't properly tuned, you will overwhelm the rest of the mix and it sounds muddy. This happens very easily with the low end frequencies as any producer will tell you.
Poor quality headphones will sound almost silent at 20Hz. So you will never know if your setup is flat and properly tuned since these low frequencies are never heard. That is until you connect headphones which do render those frequencies (very few on the market, even so called 'bass heavy' headphones). This is what I expect is wrong with most reviews of the HD265. It's hard to appreciate the quality of the mids and highs if you're washing out the sound with too much low end due to poorly tuned outputs. I suppose the head-fi-ers could listen with a 50 Hz high pass filter to replicate the inadequacies of the other headphones they're used to. But really, the reason for having the HD265 is good reproduction across the spectrum with flat frequency response. What use is 'exciting' sound over some frequencies but totally lacking low end (technically it may not even be possible to amplify those frequencies with enough EQ on the other headphones without harming the rest of the sound since it won't sit properly in the mix any more).
I suspect what is called "tight, musical" bass, is really mid-bass - if the ear is unfamiliar with sub bass or the level is too high due to poorly tuned (non-flat) output then it becomes bloated and muffled since the lower frequencies can easily overpower the mid bass frequencies. On the other hand, many cheap 'bass heavy' headphones will boost the mid bass to extreme levels (since they can't reproduce the sub bass properly either, they try to substitute with mid bass loudness) and that also causes problems of bloated, indistinct bass with lack of punch or proper bass tone.
Comparing the HD265s to a good set of monitors or a club PA system gives a satisfyingly similar experience to my ears (as much as can be expected from headphones). Especially when pushed to higher volume levels (without distortion). This can't be said of many other headphones I've tried.
I would hope that musicians or music lovers who actually use and want to hear the lower octaves may also appreciate headphones that will actually play those notes (not trail off into silence or truncate the spectrum). So my comments don't just apply to club or bass-heavy music but also to jazz, classical, and all musical styles really (at least for those listeners and players who pay attention to lower octaves and care that they are reproduced faithfully).