First of all thanks for getting to this! I have probably been nagging a bit about it , but it's a function I really needed, especially for my car, since the headphones there are connected directly to the soundcard! I haven't had the time to try it out yet, but I will this weekend. What I would like to say is that in my opinion the DSP-solution would be very nice, but the sound card adjustment by tying zones to sound cards and sound cards channels (remember kX Project Drivers, where you can have three independent zones for each SB Live! 5.1 or Audigy - I love those!). Actually if possible a choice between them would be smashing, as our british friends would say.
Oh, another thing, is this related? Using the equalizer through NetRemote only controls zone 1, no matter which zone's the active. It would be nice to be able to control those independantly.
Finally there's the question of control: I use IR remotes through Girder (since Girder controls many other things) with Windows messages. I suppose that will be the way to remote control this as well. The most important thing for me is that I can control the zones without having to make the controlled zone the active zone, like Play Zone 1 and so on. But you have already thought of that, right?
Thanks again for removing my probably biggest annoyance with the world's best media player!