Matching subwoofer

In my opinion, Vandersteen has the best way to integrate subwoofers into a system.
The Debra system is often mentioned, and I know Atmasphere considers it quite good (and I respect his opinion),
But, from my personal experience, I know Vandy subs that are 30 years old, still perform as they should. Though they require the use of an external crossover, they really fade into a room when properly configured.
I am moving to the new Sub 3's and expect the equalization ability to be as good as the 4 sub method espoused by the Debra.
If I had:
The Time
The Money
The Room, 
I would try both systems.
But, I don't.😜
Bob

The best way to integrate subwoofers into a system is to bus them to a neighborhood with no subwoofers.  

My subs are less than two years old. They fade right into the room. With the lava lamp on you can barely even see them.

Have you considered an Omega sub to mate with your speakers? I use a DeepHemp 8 with my Super 3i's. Perfect match. It added that foundation I was looking for as well. Louis makes great speakers, including subs.

Thankyou Melvin, I had thought about it but still open.  Riley, the room is still lively but as much a problem now. The kefls50 in that room at the time were really not well suited. I know the room is only tolerable but was comes into play. Thankyou all for your comments.

anyone compared the rel t7i to speedwoofer, hsu or rhythmic l12? Trying to find best value. 

Buy a pair of rel t7i, set them up next to your front mains and give it a listen. If they do not do the trick simply return them. But more likely what will happen is, you will lose the attitude about "best value" and be gaining a new attitude that is more like "how long will it take to save enough dough to buy 2 more". Or maybe just the 2 will put you where you want to be. Either way, when you try this, you will be so happy that returning them will be out of the question.