placing speakers w/built-in subs can be problematic - the best location for imaging/soundstaging can often be at odds w/the best location for bass response. this is why many top-line speakers are 2 units/channel. i recall reading a couple reviews of genesis' megabucks speaker w/built-in sub - i tink it is their 3rd-from-the-top model, the 1st w/o separate sub towers. seemed to have excellent sound *if* the location/bass-integration thing could be sorted-out, which seemed to be a real challenge...
if ewe want true low-frequency response in a full-range speaker, & don't wanna blow your budget, i'd suggest a pair of used thiel 3.5's. w/their factory active equalization, these offer true 20hz extension, as well as doing that imaging/soundstaging thing that thiel does so well. even in absolutely mint condition, ewe should be able to find a pair for ~$1k. use the savings for amplification upgrade - thiels *crave* hi-quality current, & lots of it! ;~)
doug s.