I have a pair of 22L2s in a room that measures 24' long by 12' deep by 7 1/2' ceiling. Speakers are on the long wall, a little more than 2' from side wall (left speaker), about 8 1/2' feet apart and about 1 1/2' from the back wall (measured to rear port). Zero problem with bass. Too much in most cases, but I find moving the speaker forward or back in 1/2 inch increments to either add or subtract LF response significantly. I've paired these speakers with an MF 308I integrated, an Anthem Statement A5 multichannel, a Sunfire multichannel and now another MF Integrated (an A5 this time that is rated 250x2 into 8 ohms). Zero problems with lack of bass response.
That said, unless your ceiling is the culprit (I doubt it), I'd suggest trying different amps and getting the speakers a little closer to the wall by 1/2" increments to see what you can come up with. I doubt the 21L2's are that lacking considerably in bass response compared to the 22L2s (perhaps a bit, but not that much). The more current powerful the amp (not necessarily wattage), the more slam you'll get from the speakers. If you have isolation tweaks, try removing those too as I've found time and time again that they can thin the LF response, particularly with amplifiers. Make sure the speakers are level and not firing at an upward angle, as that may thin sound as well.
Try ICs next, but I wouldn't spend my money on them until I got a better amp in your situation.
That said, unless your ceiling is the culprit (I doubt it), I'd suggest trying different amps and getting the speakers a little closer to the wall by 1/2" increments to see what you can come up with. I doubt the 21L2's are that lacking considerably in bass response compared to the 22L2s (perhaps a bit, but not that much). The more current powerful the amp (not necessarily wattage), the more slam you'll get from the speakers. If you have isolation tweaks, try removing those too as I've found time and time again that they can thin the LF response, particularly with amplifiers. Make sure the speakers are level and not firing at an upward angle, as that may thin sound as well.
Try ICs next, but I wouldn't spend my money on them until I got a better amp in your situation.