@sparksgja, I lost somehow a long post when I clicked on 'review' I'll keep it shorter and try again.
On page 1 two links were provided: one by @ditusa and one by @audiorusty and I strongly encourage you to read them. The contents will clear up some conflicting opinions. This should be required reading for all.
In almost any thread on subs there are those who complain of slow bass. No such thing! They may hear that sounds seem muffled and indistinct but it is not because the speaker is slow, the driver will obey the input signal, it has no option. This is more thoroughly covered in the links mentioned.
Let me explain: All rooms without exception have modal issues with bass waves combining either in phase or out of phase and also in between creating peaks, nulls and partial nulls. An in-phase condition will result in a peak which can be 15 to 20 dB higher than other frequencies causing what is known as either one-note bass, boomy bass or slow bass because the elevated peak takes longer to decay than the rest of the spectrum. It will be apparent then that the muddle resulting is not pleasant to listen to.
This common problem can be dealt with in 2 ways by adding room treatment or by adding multi-subs or better still is to use both. When you do both you are effectively taking the room acoustics out of the equation, so what are you left with? You are left with being transported to the venue which is the ideal situation and needs to be heard.
It has been suggested to get 2 lesser subs than just one big expensive one and I fully agree. The best I have heard are servo subs available from both Brian Ding at Rythmik and Danny Ritchie from GR Research. Available as DIY kit too. I have at the moment a REL and an SVS and find SVS superior but will build a servo sub to add to the system, not for more bass but for more of the multi-sub magic 😎
If you go this route, in addition to taming the peaks there is a corresponding filling in of the nulls which are as big a problem as the peaks, Nulls are like black holes for music, there isn't any music, it's been cancelled. The more subs the smooother the response allowing you to hear all the music without having some important bits swallowed up in black holes 🤔
The subs to look for IMO should be sealed and have continuous phase adjustment which will make integration much easier. My 2 small subs augmenting some OB speakers fill my well treated 5X7 meter room with tight slamming and detailed bass enhancing not only the bottom end but indeed everything providing a rewarding and immersive experience.
I mentioned on another thread that on a few certain recordings I can hear the size of the big hall even before the music has started.