I don't know John. When I had the AKG K501s, the same as you I believe, I found the separate headphone amps to be far better with this particular set. When I tried them out of the Onkyo receiver they seemed to muffled to me. Plugged into the Creek of SOHA amp they really came alive.

Rick


"A fear of weapons is a sign of retarded sexual and emotional maturity." Sigmund Freud