I am looking to spend less than 1k total. My current collection of headphones: ATH-M50s, Image S4 IEM, VMODA M-100, Beyerdynamic Custom One Pros, Sony XB700. (Sound Isolation/Bass Head!!!) I listen to electronica, rap and metal and also do a good bit of PC gaming. I currently use a Fiio E5...

Looking to move up from my M50s and I think these cans would be my next step upward. Any ideas of where to purchase them? Used? Anyone have a set they want to sell? 

It was my first real headphone purchase and thus far I'm extremely happy with price/performance on these cans. I am looking for more sound isolation. Would there be a set of pads similar to these that can be fitted to the m50s?  

Coupled them with the fiio e5 and Love the hell out of the setup, my first true headphone purchase, I'm looking for a bit more sound isolation though.      Is there anyway to get some pads like these for my m50's? 

Hows the isolation on these?   also   Could you recommend a good/cheap amp for them?   The Denon's seem to fit what I want for massive bass but still being crisp for video gaming and metal/rap/trance music

looking for serious bass but still good mids and highs i prefer to not have an amp. what do you guys recommend?   want to run the headphones off of an xtrememusic card for mostly fps games and listening to rap,trance,metal music   for any other suggestions I dont want to spend over $250