I have found 2 motherboard options, both have 1220, the AsRock has the optical onboard while the Asus B460 has an spdif header that I can connect optical out bracket to. I know wouldn't have got digital audio thru rca, guess they say hd audio for hooking the speakers directly to the onboard outputs, just was thinking maybe it'd process well enough to be close. I use the surround system for dvds, the htpc is just for streaming. Optical can do Dolby Digital and DTS for the HD audio streams used in blu-rays and such you'd need to be able to output from HDMI directly to your receiver. If, however, you want surround sound of any sort, you're going to need a digital output. But you're only going to get stereo output regardless of source. If you're using analog audio, you'll probably be perfectly happy with the sound quality from a decent onboard audio implementation.

Generally speaking, on higher end boards since ALC1150 4-5 years ago, I don't notice a difference anymore. My ears aren't what they used to be but audio compression artifacts drive me nuts, I can still pick up on the odd muffling or distortion (usually). Keep in mind it's just two speakers, so surround sound isn't something I'm concerned about. It's really easy to switch between the two and I've done side by side tests to see if I notice any difference in audio quality. I use a pair of desktop monitor speakers (Edirol MA-15D) that accept both analog and digital input. I gave up sound cards a long time ago and have been pretty happy with onboard audio quality on higher end boards. Best you can hope for is good quality stereo audio. any kind of digital audio, no, you won't get it over the line out to RCA inputs.

Realtek alc1150 vs realtek alc887