Two subs, yes or no?

Hey thanks, and to clarify, the mcd201 can run balanced to my amp (my preference), and rcas to sub(s) simultaneously...

Music 100%, no HT, budget would allow 2 x Velodyne SPL1000's..

Overwhelming yes! Two subs fill up your space faster, and as bass waves move slower, this will make the bass seem lighter and faster, even if you went with cheaper subs. The trick will be dialing them in so that they mesh well with your mains and then making them work in your room so they aren't just "one note" bass boxes.

Hey thanks guys, this is very very helpful.

I was at my favorite dealer Ovation Audio this weekend and Mike and Rickey spoke of running 2 x mono to integrate with my xls360's..
Two things as I was not clear. When I make reference to using both rcs and balaced output at the same time, in fact it is rca and balanced out of the variable output.

The other thing is Swampwalker suggests the position as asymmetrically (one inside left main, one outside right main, for example), which is weird because this very suggestion solves my left corner where there is a door to my balcony! Problem solved.