Nope, you were not imagining it
The 1124 is not even close to what the MiniDSP has to offer. The DCX 2496 is what its replacing. Its a full active DSP solution XOs, filters, biQuads, etc.
There is no hum because there is no mixing of pro and consumer equipment causing ground issues between them.
Its all unbalanced, I can have a comletely normal setup again with all unbalanced (RCA) connections.