Back to the 861, I've never been a great fan of what is does to 2CH in its surround modes. To these ears it corrupts the 2CH output at the expense of the (rather nice) synthesised surrounds. I have got around that by feeding 2Ch into a McIntosh preamp with L/R going direct to amps and speakers but still capitalising on the 861 surround sound capabilities by feeding a signal back from the preamp so the 861 does its bit on the rest of the system. A bit messy, but it works fine using a progammable Aeros 850 remote + a few IR operated relays.
I too took this approach; this works really well. It'd be nice if Meridian offered a music surround mode that left the Left and Right channels "pure" while adding ambiance via the surrounds.