Funny that you mention a raspberry pi...

Im about to build one /beaglebone maybe , didn't really have a purpose for it, just a toy.

Never even occurred to me to use it as an audio device, but with a batterypack and all i guess it'd work great...

Now i need to figure out a way to get a raspberry pi and a dac/amp into an Altoids tin..and then use bluetooth to control it all. I doubt im going to get any work done this week.

thanks fpp.