Hex-Path is a good option, mind the isolation is only a hundred volts or whatever -- fine for signal purposes, but beware of ESD damaging it. (You could bridge grounds with a little MOV or TVS to control this.)
If I needed more, or lower cost, I might consider planar transformers -- do it all in the PCB itself. This is a more advanced option though, as you're doing the transformer design yourself, and you don't have many protos to iterate on.
I would use a pair of trifillar wound transformers in an inverter circuit. This only requires one simple driver.
An interesting option would be to abuse some CMCs (data or data/power type), driven with a few logic gates or a gate driver, to make a simple chopper; FWB the secondaries and there you go. Put a bunch of primaries in parallel -- one for each channel -- not really a need for multifilar, the dual-line kind (which are usually bifilar) should be good enough. Downside is the lack of current limiting, which may have workarounds (e.g., use a motor-driver H-bridge chip, and use its internal current limiting, or supply it with a current limiter), and of course the cross-regulation is limited by leakage inductance.
Tim