How about: the Sennheiser 598 (amping helps but not needed, replaceable cable, great soundstage, relatively neutral sound but mid-centric)
Phillips Fidelio X1 (amping is not necessary, unrepaceable pads, balanced but bassy and fun sound)
SoundMAGIC HP200 (amping is definitely needed for the 200's- they sound like the HD650's but with more exciting treble)
HifiMan HE-400 (amping is definitely needed, great bass extension but fatiguing upper mids and treble for some, a bit heavy)
Beyerdynamic DT880 (amping is needed, neutral with a slight leaning toward treble, semi-open)
HifiMan HE-300 (amping helps but is not needed, lush, warm sound)
Beyerdynamic DT990 (amping is needed, recessed mids with tons of bass and treble)
I would recommend for you overall the X1's, 598's or the DT 880's. If you have a more powerful amp, the HP200 and HE-400 are wonderful choices.
Hope this helped!
EDIT: Sorry for the typing, I can't seem to make it neat. Apologies.
Edited by Garraty - 2/22/14 at 8:50pm