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

I just found an a'gon ad for monitors with this claim: 

"The __________ are full range Studio Monitors that will
provide the entire frequency range, therefore, eliminating the need of using a subwoofer which cannot be fully integrate with speakers".

I wasn't aware such performance was even possible. Any thoughts ? ? ?  

I apologize for the late response. . . 

RE: recommendations for Dynaudio, the Silverlines use Dynaudiop drivers, for whatever that's worth. No doubt, there are other design variations that come into play from one box to another. 

RE: recommendations for sub(s): I've received very inconsistent advice from sub vendors re: subwoofer placement and because I don't have many potential places to locate a sub, I've avoided going down this road.

willemj: The room is about 15 X 20 and it adjoins a dining room separated by a wall that's about 5' tall (living room is "sunken") and an entry. Thanks for the detailed technical info re: subs. Unfortunately, as mentioned, I have little flexibility/space for subs and having to locate multiple subs simply isn't practical. 

Jon_5912: The choice of monitors rather than floor-standers was my response to inability to move furniture that would obstruct floorstanders.
Unfortunately, I do not enjoy the luxury of a dedicated listening room in my present house. Hopefully, I will in the next one! 

Thanks to all who've suggested other monitors to try.

Meadowman: Yes; I am aware of the Mini T's! They indeed look like a very promising solution but I fear WAF will be an issue. 

willemj: In fact, the SVS is one I've definitely considered. But as I've said, when I ask salesmen about the fussiness of sub placement, they always hedge their responses, which makes me hesitate. I did read the Harbeth review. . . interesting! Will have to research whether any Northern CA audio dealers stock them. Thanks for the suggestion! 

Wow-- a lot of suggestions, here. Thanks to all. This is a lot to sort through. The Silverlines use Dynaudio drivers, BTW. 

@audiotroy : your assertion that I need to go out and hear speakers brings up another point. I haven't bought any gear based upon in-store audtion for many years, following an initial experience with a system that sounded good in the store but was terribly fatiguing once I got it home. 
With all due respect, I don't see how that can work. Even if I were to lug my integrated, cdp and cables to a store, the room sound would remain a huge variable in the equation. If I'm missing something, please explain.  

@willemj : many thanks for your unflagging efforts to find a simple solution!  What you suggest does sound do-able. 

@audiotroy:  Actually, I don't enjoy trying/buying gear over and over, unlike some audiophiles I know!  As I don't have a huge budget, but have very "picky" ears, I find the process quite stressful. There are no stores in the Sacramento area that offer home demos. I'm not sure whether this is the case in San Francisco, which is  2.5 hours away. Alas-- flying to NY is not a practical option for me!  Thanks for the further explanation re: in-store demos, though. 

Late follow up. . . I bought an Aqua La Voce DAC, coupled with Empirical Audio Synchro-Mesh re-clocker and coax cable, which made me realize there's nothing wrong with my speakers!  The system, as it was configured before, simply wasn't doing justice to the speakers. Now,the bass is amazing. Round,  punchy. It goes without saying that it varies from one CD to another, but, overall, the improvement is huge. The La Voce is available with different boards/chips (see their website) but as it happens, the standard board is particularly adept at bass reproduction. This was  valuable lesson.