I spoke with HSU, I think Im gonna add the second sub early next year. Also been doing some looking. I think when I set the new room up, I'm going to use the preouts on the Marantz and go for a Emotiva XPA-5, or whatever they are selling at that point. I'd look into an amp next year too, I just dont have the room for it. I also may end up using the Marantz in my living room, and getting something else. I think whatever I use for the pre out, needs to have Audyssey MultEq XT.

Seems the proper Audyssey setup for two subs and MultiEQ (6 point), is to run a y adapter out of one sub out, then run a cable to each sub. The subs then need to be set at the same gain and positioned equidistant from the center listening position.