Please suggest bookshelf with best bass response under $4000 pr.


Lately, I've been craving deeper, tighter bass. I'd like to hear some ideas for replacing my Silverline 17.5 monitors. Is this a stupid question, due to inherent limitations of driver size imposed by typical bookshelf dimensions, or might I actually do better with another speaker? Amplification is Wells Audio 150 watt SS Majestic integrated. Source is aging Jolida JD100 tubed cdp (in new year, I plan to replace this with another SS cdp or a transport/standalone dac combo). Thanks ! 
stuartk

Proac's as someone mentioned already. 

 AudioNote AN speakers are all stand mounts and the AN-E's go very deep indeed (effective bandwidth from 18 Hz to 23 kHz at -6 dB) The smaller AN J's go to about 25hz If your patient you can get the AN-E Lux in your price range and the J's are new starting in your price range.

PMC have some very good small speakers with transmission lines that go fairly low as well.    

Disclaimer I am a dealer. I would strongly suggest you find a local dealer in addition to bryston mini T bottom end is unbelievable well under 4000 coherent transparent fantastic
Laws of Physics being what they are audition a REL subwofer that is within budget and size in your room and keep your monitors!
Look look for used Wilson Audio Duette speakers. Truly exceptional and tight bass.