Short List of the Best 20K Speakers

Parsifal Ovation by Verity Audio + two sub B-2 by Rel Acoustic ???

A second vote for the Verity Parsifal Ovation and two REL B-2 sub-based systems. That combo is pushing the upper $20K range if purchased new.

In my case the bass response improved not by replacing speakers, but with a new set of amps! Getting a good performing amp is very important to get the most out of the speakers. I was so satisfied with the bass performance I even got rid of the Velodyne DD-12 subwoofer that I was using.

A room 20 foot square is smallish? Not ideal to be square but by most standards that is a very big room.

I'm with Shadorne, I think you lust after something that is unobtanium. It is inconceivable to me that with your room you are going to find a full range speaker and a placement in that room that will give you everything from 20Hz on up. If you optimize them for very deep bass everything else will be screwed up. At some point you have to learn to live the limitations of your situation. The only possible solution with your room is a sub that you place in the ideal location to augment the very bottom or consider some digital room correction, which by the way is getting very good.

You say you really like the speakers you have, and according to specs they do 30 Hz, and since there is very little below that (unless you are doing home theater) you are chasing a ghost. A speaker that will do solid bass below 40Hz is very satisfying for almost all music. I suspect you have some imbalance in the room or upgrade fever that is causing you to miss what the Revels you have are capable of.

It seems to me Vandy model 5 would be a good choice with the 'dial a bass' feature they have...

just a thought