Will I benefit from upgrading REL subwoofer pair

Those are very small subs and your room is large.  I would go for the largest pair of RELs possible.  As you go up their line the drivers actually get faster.  Perlisten get great press.

@atanarjuat99 

Hi Nadine,

You have a complex problem. The largest component of the problem is a large squarish room. The speaker system and room have to be considered as one. Do you sit in a listening position and focus completely on the music or are you using it mostly for background while you do other things? 

@vonhelmholtz 

A drivers "speed" is defined by it's frequency response and volume. Any two drivers of similar size playing the same frequency at the same volume are moving at the same average speed. Twice during a single cycle the driver is at a dead stop. "fast" is not a good way of describing a driver's performance. The terms "dynamic" and "detailed" are better. Muddy bass is usually not the fault of the driver. The three main protagonists are enclosure resonance, poor integration in terms of time alignment and phasing with the main speakers and finally room acoustics. 

I think there’s a couple of things going on, and none of it is cabling. More likely your flabbiness has to do with changing speaker locations or room acoustics/seating.

Two 7" drivers don’t have enough surface area to provide a lot of deep bass. Combined they offer about the same surface area as a single 10" driver. You would be much better off getting a single 12-15" subwoofer with proper EQ control.

Also, the room probably has some gnarly room modes. Use the AM Acoustics Room mode simulator to give yourself an idea. Try to keep all your speakers and your listening room out of the lowest modes.

Use measurements to see what remains. When you have that you should consider:

1. Appropriate bass traps if the room modes are severe
2. EQ to clip the biggest peaks (hopefully in the sub). If you have Roon, use built-in DSP for this.
3. Plugging the ports in the Kantas to relieve them of the distortion in the lowest octaves and allowing a good sub to take over more. Some users have found that plugging only 1 gives them optimal in-room bass.
4. High-pass your main speakers (in addition to the port plugging) if possible.

You might also want to look at this blog post. I don’t know if you need a sub or not but it may help you see how measurements can help you.

https://speakermakersjourney.blogspot.com/2021/12/room-speakers-eq.html

Why REL? Other subs have variable phase, which can prove critical to integration. 

Hey thanks to everyone for their comments and suggestions. @missioncoonery ​​​​@vonhelmholtz I will definitely look up the Perlisten. I agree that the T series is below the Focals... I bought the T series when I had the KLH Model 5s in a smaller room. 

Thanks also to @erik_squires. I think you nailed with with the comment about the 2 7" drivers. I do have Roon so will experiment with that. But I can also try plugging the Focal port(s). I had not thought of that...

@mijostyn I definitely only listen to music when I am listening. I do not enjoy "background" music. I am all there when listening. Since I upgraded the REL cables, the bass is more dynamic but perhaps I am looking for more detail.