JBT
An alternative to the PrimaLuna if you have the urge to try out a tube based DAC is the Musical Paradise MP-D2 Mk. III for a lot less money. It uses the AKM 4497 chipset and allows you to use either 6 volt or 12 volt signal tube and either 5 volt or 6 volt rectifier tubes with the flip of a switch on the mother board. In addition if so inclined you can "roll" capacitors. Plus the price is about half that of the PrimaLuna. It is easily "tuneable" by changing the tube combinations. I have owned the original version with the AKM 4490 chipset for about three years and it's sound resembles the reviews of the PrimaLuna.
http://www.musicalparadise.ca/store/...&product_id=97