"My apologies in not following up. The ST300 does support PCM 5.1 audio."
This is _NOT_ true. If you play a testvideo with 5.1 channels and not using bitstream or passthrough but pcm, front left plays on back left also and vice versa. Same on right channels. So maybe the ST300 does play PCM 5.1, but not in a correct way. Still the worst audio system i've ever owned.