I have the $300 Oppo HA-2 after having had the $600 Celsus Sound Companion One, and it sounded JUST as good as the Companion One. I've also talked to one person who tried the HA-2 against the widely-praised Chord Mojo, and he also couldn't hear a difference. Not sure what you bought, but the HA-2 is what I'd get. I LOVE IT!! The sound quality, the features/options, the sleek design, the genuine stitched leather casing, etc. Premium all the way!!
I use it on my AKG K550 MK II. Like the HA-2, I've pitted it against other headphones twice its price (and more in some cases), and it too outdid them all. Premium everything, super clarity with a WIDE expansive soundstage, supreme comfort, etc etc. $400 headphones? I tried 3 against the K550 and they still couldn't cut it IMO. Got the cheap 3-year warranty too.