I'd use it to stream music from my notebook via UPNP to the AirDAC on stage with the mixer to have music between sets at gigs for the band "Key of Red".
I'd use it in my theatre room. Park it between my appletv1 and my receiver.
I've done this upstairs already using another DAC, provided a much better sound that using the output from the apple device alone.
I would love to have this hooked up to our home theater in the living room. The family would enjoy being able to stream music from our macs and iDevices, and I would surely appreciate the bump in sound quality.
I'd run it thru the main system to get better quality for streaming from the iPad or possibly use it in a secondary system for the wife. That would depend on how that debate ends.....