I sold my Denon D2000 a while back and I kinda regret doing so. Sadly they stopped making them now. Reason I did was because it wasn't a drastic upgrade in sound quality from the HD 555 as I was expecting. Bass was legendary on the D2000 though. I never could stand the Audio technica ATH M50 because they hurt my ear drums so bad. they were so harsh that I almost went deaf. Not to mention they were FLAT and DULL BORING. Nothing like my HD 555. So I don't want anything like a studio monitor again. The Senns and Denons were magic for my ears and so perfect. I like their laid back tone. So what do you guys think I might benefit from? I however use a $25 Asus Xonar DG sound card on my PC to power it. Its not audiophile grade but its close I would say. Or atleast quite high end and sounds almost as good as my previous $150 ASUS sound card that didn't even have a headphone and. And the $25 xonar DG does have a head amp. I dunno if I should upgrade from this though. The sexiest headphones I ever seen in my life was that Denon D2000. Quality was so um I guess German even though it was not a German brand.