HD600 and DT990 (600 Ohm) are good picks.
Matrix M Stage is a top pick for headphone amps, but sound quality will suffer a little if the signal is coming straight from your macbook pro soundcard, that's why you need a DAC (it's like a high-quality external soundcard) or a DAC/Amp combo, such as the Matrix Cube or Yulong U100, just make sure whichever Dac/Amp you pick has no issues with Mac OS if that's what you're using.
When I read your first post I feel like you want something amazingly warm and romantic with good bass impact (hip-hop, electronica), however I don't think that will be good for making music with in ableton as you also mentioned, I think either you should keep your Sony MDR-V6's for making music, and use your new headphones for music listening, or if you like the sound of your V6's I'd recommend the Sony ZX700 or Z1000 as that will be a complete upgrade in sound quality and still suitable for studio quality mixing.
I think you should check out reviews of the high-end Audio Technica models and perhaps Ultrasone as well, and if you've never used an IEM, don't make the mistake thinking that earphones don't offer the same sound-quality as high-end headphones, they really do, and feel more intimate. If you're interested in IEM's check out this thread
http://www.head-fi.org/forum/thread/478568/multi-iem-review-182-iems-compared-soundmagic-e30-blue-ever-blue-866b-added-7-06
A quick IEM recommendation from me, if you want to skip the amp and invest your money in something really good, would be the Sensaphonics J-phonic
www.j-phonic.com
Edit: Ok I didn't realise you were a college student, hmmm keep your V6's as your reference headphones then and get something else with good bass, warm, romantic etc.