[gallien]

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

 

[Shimmer]

FWIR the isolation is not good as closed phones go.  Also, FWIR the Nuforce uDac works pretty well with them for a cheap solution.
 
Use the search engine some, it is your friend.

 

[SpudHarris]

I love the D2000's. I have kept them longer than any other phone I've owned. They have plenty of bass but not too much IMO.
 
Isolation is ok but they don't clamp tight to your head, they just kind of rest there so I suppose they don't isolate as good as some closed cans (HD25's spring to mind). They are sweet, sweet phones and work real well with ibasso P3+ - Keepers for sure. Enjoy

 

[the search never ends]

Like shimmer said,
For gaming, I've read several complaints the big bass get's in the way of other details.
I owned the D2000 for quite some time, the isolation is poor, especially for a closed can.
And while I never listened to them on the udac, it's a tad midcentric, which would seem to make it a good match for the Denon's. For trance, I find the bass a little slow. However, for the sake of Disclosure, I really did not like them at all.