So here are my thoughts:
DC-DC ATX adapter and 12v car battery with switchable (out of circuit) float charger in a customer built enclosure. 120 watt capable. Totally battery driven so not connected to wall power.
AMD Brazos platform (18 watt dual core) fanless
E-MU 1212m PCIe sound card:
Kingston 30GB SSD:
Run Win7 with either ASIO2 or WASAPI exclusive mode.