This is the current sound desk that Imperial Union use. As analog desks go it's really nice, but one cannot help but wonder, everytime that it's used, if a digital one wouldn't be better.
I can decode an ogg stream, FFT it, FFT it back and write it to the sound card using 30% of one of my PII 450s. That suggests that I could process about 6 CD quality streams in real time. That's not helpful as we have 32 incoming XLR feeds. Also, quality ADCs output 96Khz, 24-bit and I could only manage a couple of those.
Thankfully, FFT is pretty simple operation and a Xilinx (or 2, or 3 etc) could handle all 32 96/24 streams. A quick calculation suggest that it's 4.6 MB/s (remembering that a real domain FFT can throw away half the results) and that's easy to handle.
Still, I might see if I can simulate some 3D spaces with sound in them and have a play about with feedback suppression etc.