I think a group build of a chip amp is a great idea. Simple enough for everyone. Amazing performance for the project price. And if everybody on this board has one, it provides a standard to compare other components such as pre, source and speakers.

One suggestion though. My experience shows that the chips are one of the least expensive parts of this project. About $6 each for a single unit at Digikey. A group buy on these would not save much money (saving of $2 to $4 per stereo amp). Transformer and (nice) chassis accounts for most of the cost. A group buy on these two items would have a bigger impact. Also might consider a group buy on high quality output caps too.

gar.