Okay, back at ya'. Here are a few tidbits of info, in no particular order:

The default audio things mean that, when you insert a disc, it reverts to the previous default setting, which normally is DD. If the disc has DTS, you can cycle to that option, but not all DVD's do. This may be the "dead audio button" cause: no alternate audio.

In 'setup', you should select "raw", and not "PCM". The latter is only 2-channel stereo, and could possibly be music only. One more thing: many players have additional setup menus that are only available when there is no DVD in the player. Check that out.

The only other thing I can think of is that you're only getting surround-channel audio somehow. Other than that, we're baffled. We will continue to insist that there is no way to accidentally alter a non-recordable DVD. Let us know what you learn.