Subwoofer recommendation

I have the T/9x and like it.   If you got a budget of $2k you might be able to find a pair for around that figure.   If your going for one you might be able to step up to the Rel S/510. 

I also have velodyne micro vee and it works well for modest HT duties. 

People have had success with SVS as well.  I tested them , like the phone app but ultimately chose the REL.  

I am not an expert but am happy with the Rythmik sub.  I have a F12.  You could get a couple for $2500.

Jeez, how big is your room?  +1 @12many on the Rhythmiks.

It would make a lot of sense that you first determine how low your speakers go in your room. I would get an SPL meter and measure. When you find out what your cut off point is, then you can make a better decision as to what you need. I don't think you can do this by guessing. SPL meter will also help you integrate your sub much better than any ears could do. I hope this helps.

Used Paradigms

Vandersteen 2wq's are available for under $2K for a pair, but you need the crossovers ($800/pair). Just follow the directions and you'll have the best integrated subs you will ever know.-And, they will perform without issue for years.

Bob