Uh, seriously, buy a decent receiver. Like, today. ;\)

You've got $500 pair of speakers and a $350 set of headphones there. They deserve more than a $10 garage sale receiver.

Something like this (refurb Denon AVR687 for $139) would be far, far, far superior to your garage-sale special and should be affordable for just about anyone.

And to be really honest, those AKG701's ought to have their own headphone amp if you really want to hear their potential.

M80v2 | VP150v2 | QS8v2
SVS Pci+ 20-39
Emotiva UMC-1 & LPA-1
M22ti + T-Amp, in the Office