spot on .. I haven't done any further testing, but I have done some reading in the rdp protocol and how that may effect sound.

TiVo Desktop (software) DOES run in userspace, and presumably uses the sound card to transcode; when I RDP I redirect all sound functions to the machine I am rdesktoping in from, removing this function from the tivo machine (and therefore removing the sound card that tivo desktop software uses)

I have already installed a vncserver (coz the garage is sooo far away, and I must preserve my couch grown lard ars3 )
This weekend I will try locking the desktop (from the console) and see what is affected, if anything.