Separate names with a comma.
-Please delete, moved to correct section, my bad.
I'd get the USB to SPDIF. It has circuitry to communicate with the host PC, and transmit the electrical data as an optical signal, but as far as the data itself it's still lossless digital, so the circuitry doesn't degrade anything.
In many cases a receiver will use an ADC on the inputs so that it can send it through the DSP. You may not get any benefit from an external DAC since it may have to go through the receiver's ADC and DAC anyway.
Hifimediy DAC, should not have to spend more then $70, or as little as $30, for a USB DAC.
What speaker setup, do you have for the Yamaha?
2.0 or 5.1 or other?
I've moved this thread to the help section, but i havent missed your reply, thank you!