in order of preference re pure sound quality only
all still here
Beyer DT1350 - Tonally stunning, most neutral headphone I've heard so far, insanely short decay, it can handle any amount of splashy midrange pads and synths and keeps them all under control. Very revealing of source, but rewards you when you have it. One of the only headphones I listen to anymore, actually; it spoiled colored cans for me forever and started my love of linearity. Not the biggest presentation, which leads to my second pair, but it's big enough for portable use, and the seal you get with these is phenomenal. There's too much for me to gush over here; every section, the DT1350 excels at, bar the aforementioned soundstage/width.
Nice...I've had mine for 6 months just about and still am amazed every time I put them on my head. To date, the best $270 headphone Ive ever heard - portable or otherwise.
Pioneer SE-700: Best headphone I own so far. Nice detail retrieval, a good sense of rhythm, nice imaging, and nice airy sound. A little thin at times. Bass is just not there, which makes a few songs less exciting. Mids are nice and smooth, never nasally or boomy. Highs roll off at the very top but are otherwise quite nice. The sound is overall very smooth and flat. Very fun to listen to despite their analyticality. Unamped, they are unlistenable. Out of my E7 they do get better, but not as good as they could be. Driving them from my desktop subwoofer's speaker taps kills what bass they do have(as the subwoofer has an internal equalizer to keep the bass out of the satellite speakers), but makes everything else sound absolutely unbelievable.
AKG K240 Studio: Warm. Moderate detail retrieval, moderate attack and decay. Small soundstage, meh imaging. Tight, controlled, airy bass response. Liquidy mids and highs smoother than butter. Some of my denser music (such as Psyborg Corp.) turns into a disgusting mess on these. Not good for all genres. Most comfortable headphone I have ever worn.
Pioneer SE-500: Basically, everything the SE-700 is like, but worse in all departments. Had these before the SE-700s. Loved them too before I got the 700s.
KOSS K/6x Plus: First "real" headphone, got from a garage sale for $10 when I was 12. Bright. No soundstage, no imaging. Skeletal, light design makes them fall off my head easily and makes it sometimes hard to get a good seal. Very tight bass that reaches low but not very low, stops around 13 Hz. Sparkly highs that are a little bit rough. They are neutral with a slight tilt towards bright. Very well-detailed.
Audio Technica ATH-M50: I really don't like these anymore. Meh detail retrieval, meh attack/decay. Midbass hump, fairly tight low end but not as good as it could be. Absolutely disgusting midrange, heavy distortion and roughness throughout the entire range. Highs jump out at you, scream in your face, and smack you across the cheek. It's not quite harsh, but it is definitely noticeable and to be honest I don't enjoy it very much.
Audatron SH-608R (heavily modded): I took the driver off the baffle and secured it in the back of the earcup. I removed the original pads and substituted AKG pads. I messed around with the damping a lot and removed the two volume potentiometers in the earcups. Doing this made the sound airy and delightful and made the soundstage huge. They still have no imaging, however. The bass is no longer suffocating and the mids aren't boomy anymore. They're basically a worse K240 Studio, with less treble and more bass. Pretty bad but they have more bass than any headphone I have so they still get some use.
Audatron SH-608R (stock): Absolutely atrocious. Muddy bass that overwhelms the other ranges, boomy mids, no treble. Sound is very suffocating and oxygen-deprived. No soundstage and no imaging. Slow attack and decay and meh detail. Pretty heavy. Bad isolation, but better than most. Uncomfortable as sin. Thin supra-aural pads and way too much clamping force. Only redeeming qualities are nice, tough build quality and appealing visual aesthetics.
KOSS Reference One: Just got these yesterday. Huge KOSS cans from the 70's. The bass reaches low, the highs are sparkly and smooth, and the detail is good. Absolutely massive soundstage with good imaging and instrument placement. They're heavy and built like a tank. They squeeze hard and isolate better than any headphone I've ever heard, and they don't leak at all. They seem to be extremely analytical... not sure how to rank it yet though.
Technicalities Ranking (preference depends on genre):
1) Stax Omega MK1
6) Denon AHD-7000
7) Grado RS1i
1) Westone ES5/UM Miracles/UERM - too difficult to say which, if any, are best
Is 5) the old iBuds or the new EarPods?
1. Monster Miles Davis Tribute
2. Monster Turbine Pro Gold
3. Meelectronics M11+
The MDs are my favorites and they never leave the house. The Golds are my going to work and around town drivers. And the M11s are my mowing the lawn and yard work drivers.
I can not really rank them as I use each them for different music and listening enviornments:
Senn HD600 Toxic Silver recable- alone at home for soundstage and detail
Dennon AH D-5000- At home if some ambient noise, great bass, good detail
Ety ER4S- portable rig or at home if the girlfriend just will not shut up...