PC music to AV receiver


Apr 30, 2013
Hi guys, so I have this sweet set-up in my living room but I need help getting the best audio quality possible from my PC to the receiver. Currently, I have my pc hooked up to the receiver via HDMI. I don't have a sound card, but can get one if it is recommended for this set-up. The majority of sound files on my computer are 320kbps mp3s. I do have some high quality flac, wav and dxd files. What is my best choice (keep in mind I'm trying to save money) and what will I need? Thanks.

and btw, having video go to the receiver isn't a necessity for me.

My setup:
Polk audio 5.1 surround sound or stereo for 2 channel music. Doesn't have to be 5.1 if that won't work.
Pioneer VSX 823k
Custom built PC with HD 5770 graphics card (hdmi to receiver)
NO sound card.