The amp does very well with many headphones, but admittedly it makes Grados sing and is optimized for those. It does great with KSC-75's, Senn HD-25's, and Sony V6's, all at the higher impedance setting. While I don't have a pair (yet!), I can attest to the fact that the Denon 2000's come very close to Grados in having an affinity for the Torpedo. They sound marvelous through the Torpedo! I haven't listened extensively with Senn Hd 580/600's, but I will try to do that in the coming days and report back.
I have the K701's and I'm not sure those are as good a match. If you're familiar with those phones, you must know they are very persnickity about amp choices and in my experience, tend to favor something that can put out huge current impulses on demand (high Class A bias SS or hybrids).
Edited by tomb - 11/13/11 at 11:39am