Connection for Surround Sound, Multiple Inputs?

[alandbush]

I've been searching for years for a surround decoder which can separate front and rear channels from a soundtrack and send them to independent external DACs *digitally*. It would help me exploit my Phantoms better in my surround setup.

Have you considered the Meridian HD621?

Not a surround decoder as such but will split HDMI audio into 4x digital stereo pairs.
Preface that with a miniDSP nanoAVR HD which will allow trim and delay adjustments etc. to be applied to HDMI audio and this may provide a solution of sorts.