While I realise that this is a very old thread now, I'm posting this in case someone else has the same problem with PCM and bass that I had. As it turns out, Onkyo were fairly useless when it came to helping me with this. I never received a reply from the guy who said he'd investigate, even after I sent a couple of follow-up emails (each one over a week apart, so I wasn't constantly bugging him). Anyway, after playing with every obvious setting on the amp I turned off the auto lip sync feature on my TV (God knows why I thought to do this) and the bass on PCM returned. As an experiment I reactivated it on the TV and disabled it in the amp and got the same result. So, as long as auto lip sync is disabled on one of the components all is well. Luckily I don't get any sync errors, but it can be adjusted manually anyway. Odd that the auto lip sync feature would cause these problems. All three devices (player, amp, TV) are HDMI 1.3, so you'd think it would be okay... It's also very strange that it doesn't affect any of the Dolby or DTS codecs (be they lossy or lossless). Anyway, obscure thing to cause lack of bass. I wonder if it's peculiar to Onkyo amps?