I mainly use Beyerdynamic DT-770 Pro or Sony MDR-V6. I don't own any Grados, and they're much different than the headphones I use, so I can't comment on that. But my Sony's benefit greatly from the tube amp and it helps alleviate the bright/synthetic feeling while still maintaining a reference-quality sound. And I'm almost always wearing my DT-770s which are very bass-heavy, and the tube makes its sweet bass a little bit sweeter.
I was looking at all amps in the $200 pricerange when I bought mine. With audio equipment, you can spend anywhere from $5 to $5000, and the money will match the quality. So I just set a price and seek the best quality at that price.
(also you don't have to make 3+ threads for the same general topic)
Edited by alien3456 - 11/24/10 at 9:58am