Niles IntelliControl ICS Multiroom Audio System

Taking a cue from PC's, the Niles IntelliControl Multiroom Audio system is a 12 channel/6 Zone expandable audio distribution system. It uses cards to expand its functionality. Of course an iPod expansion card is available and other systems such as XM, line level inputs and traditional FM/AM radio are all available. Wisely, Niles has chosen Cat-5 cable for signals and 4 conductor cable for speakers. You can expect a well rounded system for around $4500.

From the article:

I loaded my GXR2 with the maximum six cards,
using each of the cards Niles offers and doubling up on IM-AUDIO cards
to handle my Escient and digital cable box. The system is expandable to
a total of 30 separate music zones by connecting additional GXR2s. Each
adds another six zones that can be independently controlled, though
you're limited to the original six sources; these "slave" GXR2s are
outfitted with IM-AUDIO cards to "cascade" sources from one unit to the
next. If 30 separate audio zones were actually needed in a home, six
sources would likely be a limitation, but this probably won't be a
concern for most users.