The more, the merrier! Initially buying one 1100X and a 800X just to try out, I ended up buying three more 1100X subs. The primary goal at the time was to create a couple stacks to blend to my Expressions which have a great amount of bass, but I wanted to find out if more woofers would "fill" my large room with more finesse. The short answer is yes! Each Expression now has a pair of 1100X subs stacked about 1" away on the outboard side of each. The bottom with its feet, the top with no feet and a rubber membrane between them for great stability. After a bit of tuning that really wasn't too difficult the result is way better than I expected! I turned down the Bass Control Knob on the Expressions all the way to -10dB which makes the 1100X subs work up to around 90Hz, well, one of them, the other is at a lower setting. Each sub has some unique settings and some settings are shared. I was expecting some improvement in overall feel in the lower bass and maybe more articulation, but there's more. First, at low volume, bass is never shy but is still very accurate sounding. Second, there's way more dynamics with greater impact. Improvement in dynamics is a very welcome and happy result! Music is even more real than before, and presents with greater ease, seemingly effortless, no strain. Finally, the soundstage is slightly wider. Where's the 800X ? At the back of the room. The bottom 1100X of each front stack and the 800X in back are connected together via an outboard controller to create an LFE Group for movies. The input used on each sub is the LFE input. With this group assigned as LFE in the processor, only the .1 LFE is sent to this group, so Bass Management sends the bass below the crossover settings for the Small channels to the Large Fronts. It's a great arrangement! The app helped so much in the tuning phase. What took hours would've taken days otherwise. I truly don't know how I could be more satisfied with the result!