Also, it seems some of your worry on UI has to do with not so with it users forgetting to turn up the volume on their external speakers. You (Steve) showed an example of your laptop which has a "potentiometer". Problem with a potentiometer is their physical manifestation is stateful. Why not mandate stateless volume control devices like a V-Pot so that your software has complete control. For the masses that don't know what a V-pot is (virtual potentiometer) you can see an example here: Mackie V-Pot (note V-Pots have been around a long time, so Mackie did not invent them - though they seem to suggest so on this web page)
Yes I realize that you would have to create a new remote interface between audio cards and remote amplifier/speakers but I think that would be of added value and something that *is* patentable. <ducking> If you all were worth your salaries </ducking> you could even try masking this information in a wide-band low volume signal on top of the audio channel so that existing audio connectors wouldn't have to be redesigned and the signals would be imperceptible by any human. Caveat, I would actually be surprised if this technology hasn't been invented yet.
Lastly, quick question, what's going on with DirectX DirectSound/DirectMusic? Are they going to be intergrated into WAVE? <edit> and how soon? </edit>