Hi there, I was just wondering how good of quality is, since my family just got a new tv that supports optical audio and we have a cable bx that supports it
If your TV is hooked up using HDMI, use HDMI sound. It is all digital anyway and HDMI does 7.1 uncompressed while SPDIF only does uncompressed stereo and 7.1 compressed.
Won't be as good as HDMI but unless you have a bunch of fancy gear or 5.1/7.1 speakers you will never tell a difference. even then you will only tell a difference if the source audio is surround.
If your TV is hooked up using HDMI, use HDMI sound. It is all digital anyway and HDMI does 7.1 uncompressed while SPDIF only does uncompressed stereo and 7.1 compressed.