Hmm. Well, out of the cans I've owned or, with reference to the R10, CD3k and RS-1, long-term borrowed (all single-ended and not balanced):
Class A
I'm guessing Sennheiser HE90 will go here, but can't really say 'til I get an amp...
Qualia 010
AKG K 1000
Sony MDR-R10
audio-technica ATH-L3000
Grado HP-1000
Class B
Sennheiser HD650
Sennheiser HD600
Sony MDR-CD3000
Sony MDR-SA5000
Grado RS-1
Grado PS-1
audio-technica ATH-W11JPN
Sensaphonics 2X-S
audio-technica ATH-W10VTG
Class C
Grado SR-225
Grado HF-1
Shure E4c
Shure E5c
audio-technica ATH-ES7
Sony MDR-EXQ1
Class D
Koss KSC75
Sennheiser PX200
audio-technica ATH-ES5
UE superfi 5 Pro
Otherwise if I've owned it and don't list it, guess I'm really can't recommend them.
tho the reasoning for such differs...
Anyway, them's the thoughts. I can certainly respect a few other lists in this thread as being different here and there but all in all in line with my experience as well.
Best,
-Jason
Postscript: hmm, this list is rather Stax deficient... probably ought to give more time to AKG and Beyers ... sigh, not done yet...
Post-Postscript: lol, I just re-read the list. Man, I have to say my recommendations seem so conventional! But that's what I think!
Post-Post-Postscript: Also I've only had the HP1 for a few days and it's increasingly impressing me. We'll see if it breaks into Class A for me...
PPPS: Moved the HP1 to Class A. It's clearly worthy.