Will this amp trick work for increasing bass performance?

@oldhvymec
I was suggesting the X250.8 for bass duties and XA60.8 for mid/high.
But please enlighten me. I'm here to learn something, not to get fried haha.

I'm looking for a way to get more deep bass from my system. What do you suggest?

@millercarbon Thanks for your reply. I was not aware a "$3k DBA" could solve my problem. I'm new so please elaborate a little; which one would you recommend? What is a DBA to begin with? I'm very open to other ideas.

@gregm Thanks for your feedback. 2 Subs may be an idea, since with 1 sub in the corner I found the sound too muddy. No coherence, timing off. More bass, yes. But once I switched off my sub, the music fell back into place again. 2 subs would be stereo, symmetrical and may perform better.

Thanks @gregm 
I can't send direct messages to @Audiokinesis. Not sure how to reach him on this forum... :(

@onhwy61 Thanks for chiming in. Any suggestions for a good equaliser?

Anybody an idea what @millercarbon meant by a “$3k DBA”. Any links to a product like this?

Thanks all, I'm learning a lot! Few points:

1) It's a living room set up, hence my preference to not have multiple subwoofers around;

2) I've tried adding a single sub. Enough bass but too muddy, and for me too difficult to get it right;

3) The 11 inch woofers in the Focal are plenty powerful, but they don't get engaged enough. Simple bass and treble control, like in my car, would do the trick;

4) @oldhvymec I'm not spending an additional $30k+ for bass. That's including an amp I'll need anyway. It's either X350.8 or X250.8 + XA60.8, with the latter costing "only" $4k extra;

5) Not hung up on Pass Labs. Although pricier, I'm also considering Ayre KX-R with VX-R or MX-R;

6) My only source is streaming Tidal (via Roon in future) and I'll probably choose the Ayre QX-5.

Question:
To what extent would a high-end equalizer degrade the quality of the signal? Would you notice the extra component in the pathway, even with the EQ set to flat?
I don't mind the extra cost and an EQ will sure do the trick. But if my sound quality is seriously affected, it may not be worth it. Easy enough to try though.

@georgehifi Thanks for the suggestion! If it's very transparent, it can't hurt to try it out. Currently I use XLR from pre to power amp.
Using this tone controller means I have to go RCA all the way right?

Would changing from XLR to RCA make any difference?

@pwerahera Thanks for chiming in. It's not a dedicated listening room; it's my living room. It's 30ft wide and 28ft deep, with openings to the left and back. The X and * mark speakers and listening position:

                        30ft
             -----------------
             |      *       *       |
---------           x           | 28ft
|                                    |
---------           ----------
             |          |            
             |          |  
             --------

Thanks @onhwy61 , I just found this https://apps.apple.com/us/app/boom-bass-booster-equalizer/id1065511007

I'm out of town, so I can't test this at the moment. Looks promising since Tidal is my only source!

@mkdm11 Thanks for sharing, are you bi-amping the XA60.8? Please elaborate on how/to what you connected each power amp

Guys, what about a pre amp with a built-in EQ, like this McIntosh MA9000 https://www.mcintoshlabs.com/products/preamplifiers/C53

@onhwy61 You mentioned tape loop. Like this "tape output" https://www.ayre.com/wp-content/uploads/2018/05/KX-R_BACK_Web.jpg

And how/where do I add the equalizer in that scenario?

@gdaddy1 Did you say "connect them [subwoofers] directly from the speakers". Can you elaborate on the exact wiring in this scenario?

I play Tidal via Chromecast to my streamer, wirelessly. I also have a AudioQuest Dragon Cobalt that I attach to my iPhone or MacBook, then via a 3.5mm to RCA to the pre-amp.

I got suggested that Roon can play the Tidal library too, which superior results

Thanks @audiorusty, will keep that in mind. 
Just auditioned a McIntosh pre amp with built-in EQ. That solves my problem in one go.
Someone said an EQ downgrades the quality of the music. “So does a room”, was the sales advisors reply. “It’s a very small trade off, but think of the EQ as a room correction tool”. My system will be in the living room, so I’m very limited in terms of room treatment. 
Also looking at Wilson Audio Sasha and Alexia Series 2 now. They only spec the minimum power, not maximum.
The Alexia’s had muddy, boomy bass despite the room being properly set up. The sales rep assured me it’s because the 350 sq ft room is too small. And this won’t happen in my 860 sq ft living room, with large openings to the kitchen and study.