Have no experience with HPNA, but I've run ethernets with over 50% saturation. Not to be recommended. That's why I use switches (not hubs), and at least 100M between the switches. No problem supporting dozens of *video* streams.

Five receivers, all receiving uncompressed CD, is not very different from five PC's showing MPEG2 2Mbps video. And I've sucessfully done that with 15 PC's.

Anyway, can't imagine when I would like to have 5 *different* streams going on in my house - I can imagine having one stream into the main hi-fi system for *real* listening, and another "background listening" stream into the rest of the house, but when I go from one room to another, I prefer for the *same* music to continue. But the receiver probably doesn't handle multicast either.

Storing it is easy - with 160G IDE disks, and good multiple-IDE RAID controllers, it's not too expensive and hard to put together your own 1Terabyte server.

More than happy to take you up on the MP3 vs. WAV challenge. I can definitely hear the diference on the Linn Isobariks, but usually I can hear it on the movie room Tannoys as well, and even after a couple of glasses of wine. At 256K.
Let's do a listening test next time you're in Amsterdam

Julf