Subwoofer SVS SB13Ultra vs JL Fathom F110V2

one other sub to consider, especially if you have a large room, is Seaton Sound.  I've owned subs from Velodyne, Vandersteen, JL Audio, SVS, and now Seaton, and find that my F2 outperforms all of them.  Absolutely nothing wrong with the others, especially JL and SVS, but I find the Seaton to be better all around.

Rythmik also has a loyal following - I was considering the F15HP when I purchased my Seaton F2.  I'm sure it's another fine option, but I have absolutely no regrets nor desire to try any other subs since integrating my F2.  It's an amazing sub.

The Seaton website is in progress, but as you noted the forum is updated and you can always call them at  773-290-8436.  You could also email, though it may be a day or two to get a response.  I've always found them to be great to work with on the phone.