I have a Schiit Vali/Modi combo with my Retina Macbook Pro that's working very well for music. But I also want to use the HD650s for my tv watching late at night (so as not to wake my wife). I have a Denon AVR-1312 receiver for my TV setup (with RCN Tivo, Apple TV, and Xbox 360 hooked up to the receiver) and it sounds fine, but is there an inexpensive way to get more out of the Sennheisers given my setup? Keep in mind that the tv watching will be actual television and gaming, not music primarily.
 
Thanks!

I don't think your receiver has any line outs, does it? So seems like your only choice is to use the headphone jack on the receiver.