I am currently running SVS subs with my Aerius i's. I ran 2 SVS 16/46pc's for the past few years. Just last week I put two 16/46 pc plus subs in to replace the original 16/46 pc subs.
These subs are very quick and keep up well with my ML speakers. For two channel music I use tube equipment and then it goes to subs, then to the speakers. Really sounds good. I would recommend SVS with ML from my experience.
I think the SVS tube subs are immensely ugly, but it's all in the eye of the beholder... Having said that, I have been using an SVS CS-Ultra for years now and have never heard anything better for movies. For music I have however: Velodyne, MartinLogan, Revel.
I second that. For many years, we have had a nearly-all-Martin-Logan system, with Quests and Logos in the front, and Aerius in the rear, plus two 1500-series Velodynes. One of the Velodynes recently blew, and we were about to upgrade to a pair of used HGS-18s (the last good Velodyne series) when we found out about the Descent. We listened to a Prodigy/Descent pairing, and the difference was striking--the Descent is so fast and so accurate that at first we thought it was bass-shy, until we noticed that (seriously) my pants leg and her hair were both being pushed around by unseen forces. It turns out that while the Velodynes have been pretty good for bass, they distort more and they're not as quick, and so we have been listening to booming and muddiness without being aware of it, because we didn't have anything else to compare to that sounded any better. Now we do, and so now we have upgraded to two Descents (and we wound up getting the Prodigies as well, so now we have no money). If you haven't heard the Descent, you owe it to yourself to find a proper Martin-Logan showroom and listen. I was skeptical about smaller drivers being able to move enough air to have an impact, but with three of them, the volume works out to be about the same as an 18" cone, but with much higher accuracy--and the excursion on the Descent drivers is generous anyway. Add to all of that the fact that Velodyne has joined the dark side (emphasizing home theater effects over accurate music reproduction, and now doing it with digital), whereas the Descent was designed first for music reproduction with home theater as a secondary consideration (but it does a great job on home theater), and there is no contest. And then add that the Descent is engineered from the outset to work well with Martin-Logan speakers, and the choice is a no-brainer. And I was a very happy Velodyne owner for many years.
I totally agree with happybuyer. I have had my Descent for 3 days only and it is getting better. I first thought it was bass shy and I turned it up and thought it didn't blend with the panels. I have turned it down again today to only level 3 and +1.5 db on the 25hz knob and it blends perfectly with my Quests panel. It is so strange that it seems to make my whole midrange sound smoother with an unbelievable huge sound stage. Worth every penny... I am jealous though of happybuyer. I would love to have another one!!