None. I should say I'm enjoying the better sound I get from this little box than the bigger more expensive box it replaced. DAC, power, whatever. This is USB powered, but you are right, I lack the evidence to prove my overall belief.

I can live with that.

Panny 3000 PJ, 118" Carada, Denon 3300, PS3, Axiom QS8, PSB 5T, B&W sub, levitating speaker wire