I just want to use the best DACs possible.
I'm assuming that most "receiver" devices have analog and digital outs.
I have some very high end DACs that work as stand alone hardware, so that's probably the best bet...
The reason I went down the though road that I did, is because you said USB/FireWire. DACs that interface that way will only work when directly connected to a computer. These little stand-only clients mostly have analog outs. If they have digital it's going to be S/PDIF. So the DAC would have to support that too.