This sounds pretty basic - put a truly full range loudspeaker in a room and you end up with less than linear bass response at a listening position. It's not the speakers fault, it's room accoustics - it happen very often.
You need to correct the frequency response issue - you can move the speakers around - which will help, but most likely never give you linear , true full range bass response. Being 11 feet out in the room will definately reduce your low bass output - if you push the speakers closer to the wall behind them (try around 4 or 5 feet), you will see a definate increase in extreme low end. 11 feet is WAY to far out into the room.
Option two is to correct for the room anomolies via active room correction of some type. The third is to add a subwoofer to give you more control of the low frequency response, and to sort of overcome the room issues with brute force. If you do this, you will need a woofer with prodigous output capablity - The watch dog's do not have enough extreme low end output, in my opinion to do this. Don't forget, they are only 12" woofers - only capable of moving so much air, and they tend roll off the very bottom anyway - they integrate beautifully with music - but they are not brutes. You already have much more air output capabilty with the MAXX's, as it has 2 13" and 2 10's - so adding 2 more 12's isn't really all that much.
The reason to add any subs to a speaker like a MAXX is to augment in addition to the speakers low bass, and be able to "overdrive" the extreme bottom end to help with the room loss. I would want to have the output of at least a pair of 15's for this task. Actually - I would rather use a really good digital eq before getting into the subs anyway, as it will allow for correction over more than just the very bottom octave.
In my store we have NEVER had linear bass response below about 35 hz until we had active room correction. In 2 different rooms with many truly full range speakers, we never got below about 35hz and always had plump sounding upper bass - no matter where we moved the speakers to. Active eq or room correction has been the only way to extend the low end response and truly clean up the upper bass.