As for an SE out, L+, R+ and gnd straight back to the power supply (not to the amp boards). Either use 2 conductors for the gnd, or a heavier wire (usually 24ga for signal, so maybe 20ga for the gnd).
I wouldn't use an epsilon 12 with this, as it won't properly handle balanced signals. I'd use one of Kevin's balanced protection boards instead.
400mA sounds about right (don't recall exact figures, but it's probably here in the thread somewhere).