Isolation is not great on the D2000 and non-existent on Grado phones. I haven't heard the Ultrasone but you may like the HD25-1ii, which has quite good bass. A E11 is sufficient to amp it. The biggest problem is that the HD25-1ii is pretty tight on the noggin, though that does lead to some excellent isolation; they are a classic in studio use, but not the most comfortable for long sessions. I'm not a fan of the HD251ii mids, but that shouldn't hurt you too much with your music selection, though honestly I don't listen to much of those genres. You may consider the ATH-M50 as well.
Thanks. I was kinda thinking the same about the denons myself. Although I must admit I know nothing about the Grado's. I keep hearing good things about these ATH m50s but what turned me away from them (i thought) was the slow response. Is this true?
On a side note im a not well educated when it comes to portable amps. however, the thought of having a USB adapter for listening from my laptop sounded appealing. I would not want to sacrifice the "portability" of it though because its mainly for my phone.