Hi,
My current headphones are AKG K141s. The sound is nice enough to my inexperienced ear but they are damn uncomfortable, so I'm about to buy something better. To give you an idea what I like/don't like I'll just go through which other headphones I've used/owned -
Grado SR80 (32 ohm) - too thin, bright and uncomfortable, with a narrow soundstage
Sennheiser HD565 Ovations (150 ohm - used without amplification) - very good but don't excite me somehow - top end can be a touch harsh
AKG K141 (55 ohm) - Nice, rhythmical but too bassy, coloured and uncomfortable
Koss Porta Pros - Limited but exciting
CX300 - harsh mids, can sound distorted, microphonics
MX500 - plain poor, majorly lacking in bass
EX71 - boomy bass, harsh top end, microphonics
KSC-75 - great when modded to press on ears more, same exciting sound as Porta Pros
I should mention my music tastes as well - mostly pop/rock with a bit of jazz + classical thrown in. Music I'm into at the moment would be - Muse, Radiohead, Killers, Beta Band, Catatonia, Amy Winehouse, Madeleine Peyroux and other similar stuff.
I don't have a headphone amp and TBH I don't want to spend the extra to buy one, so we're only looking at how headphones will sound plugged straight into my Marantz CD6000 OSE LE and my PC. I also don't like closed headphones, or headphones that rest on the ear so we're looking for open-back circumaural. Here's what I'm looking at-
Sennheiser HD600 (300 ohm) - the question here is are they still good without amplification, and do they suit my music?
AKG K601 (120 ohm) - again I read they need amplification
Sennheiser HD595 (50/120 ohm) - high sensitivity (112) may be a problem - may be too loud with my CDP based on how loud my K141s (sen:103) are on min volume (assuming those numbers are comparable)
AKG K240 Studios (55 ohm) - likely to sound quite like my K141s, not exactly hi-fi
Beyer DT880 (250 ohm) - high impedence a problem?
Beyer DT860 Premium (32 ohm) - don't seem to get discussed much versus the higher impedence Beyers, plus I've never heard any Beyers
Audio Technica ATH-AD900 (35 ohm) - know very little about these but they tick all the boxes
Audio Technica ATH-AD700 (35 ohm) - same as above but cheaper
Really could use some guidance here

Cheers, Simon.