You're probably best going for a MiniDSP 2x4 HD, if you keep the leads short there shouldn't be a problem using RCA connections. I'm not sure whether MiniDSP do a balanced version with USB audio input.
If you do go for the 2x4 HD make sure to update to the latest firmware, doing this fixed a few problems on mine.
If you do go for the 2x4 HD make sure to update to the latest firmware, doing this fixed a few problems on mine.