Subwoofer to go with Wilson Maxx II's

I'm in the market for a Sub to compliment my Maxx II's. I thought I wanted a powered Watchdog-and still may. I read a review that said it may be-choke-inadequate. Never thought I'd hear anything written about Wilson's with that word in the same sentence. In it's defense, reviewer was referring to below 20hz sound in home theater. I like movies, but my main emphasis is music. Any recommendations or comments about the Watchdog?
Assuming the Maxx 11 really need a sub I would look at the REL Studio and use it in parallel with the Maxx woofer and set to the lowest possible crossover frequency. But are you sure that you really need one, what is the Maxx 11s bottom end cut off? The smaller Wilson's I have heard do not seem bass deficient.
I've heard the MAXX2 extensively, and I can't imagine needing a subwoofer with those speakers for music or movies.

For home theater use, where you have a dedicated subwoofer channel (e.g. 5.1), a sub might be called for, though I think it would take quite a sub to mesh well with MAXX2s. In that case I like the JL Audio F212. I talked a friend into one, and the F212 can produce enough clean output with a 20hz test signal to make you truly nauseous. The F212 is a monster.

But if I owned the MAXX2s a sub would be the last thing on my mind.
31.5in fostex super woofer. Would be my suggestion a good step up from drivers used in all commercial sub-woofers or bass systems.
The Wilson's go down to 20hz with smooth response. I've actually had people think I was using a sub when I wasn't. Best speaker I've ever heard. But believe me, there are times I may not "need" a sub, but want one and appreciate one. I had a Bag End Pro 18 and it went down to 8 hz by use of an electronic synthesizer, but lightening got it, so I'm looking for something to replace it. The Bag End was good. You could "feel" the room vibrating on tests CD's, but couldn't hear anything. Must be what an earthquake is like. Looking for something more musical and quicker. A class "A" biased amp would be good connected to something that could handle it.
I have a friend with speakers that don't really need a subwoofer.......they already do 20hz or so (Apogee Scintilla)

He added The Thigpen Rotary Woofer (Made by Eminent Technology) to his system and couldn't be more happy (5hz bass).

He says the rotary subwoofer is the best subwoofer in the world........looks like you can afford the best?

Edit: talked to my friend tonight for the first time in a while. He now has mbl 101 - MK II speakers, and two of the rotary subwoofers.

Make sure the sources your going to use go down below 20hz.CD players in the 80's used to say they went down to 5hz,but some newer high end CD's and DAC's only go to 20hz.
Oppo BDP-83& BDP-93 low limit is 20hz.So these won't work with analog out for movies.I no they're not hi-end though.
I had Maxx 2's and a REL studio 3. Now I have Alexandrias and a pair of JL Audio F113's. My current bass is FAR superior to what I had previously. I think it is important to know what you are trying to achieve. In short, I would get a pair of appropriately sized for your room JL subs. The bass on Maxx 2 is ample and good, but there is better out there. I found that the bass could get a little loose at times. Also, they usually don't go below 30hz when they are placed into the room as most of us do. The JL's room correction will improve the linearity of your bass, and they will go lower. After you buy them (get a stereo pair) and set them up, let me know if you still think the Maxx's were going down to 20hz.
We upgraded our demo theater from a Wilson Watchdog to a JL Gotham and have not looked back! Big room, and the Watchdog did not cut it at all. It was the passive model powered by a Classe CAM600.

Maybe you should get Wilson Thor's Hammer. :)
You would not really want a Class A amp as a sub amp. they are hideously inefficient and their virtues would not be important and their vices magnified in a sub application. You need a lot of power and what the amp does outside the bass region will be largely irrelevant.
Stans on the right track. 'd' amps are a natural for sub duty. Any switching artifacts or need for a Zobel on the output are simple non-starters.

That being said, and I KNOW it is not a match or real alternative...but my HSU will easily shake the house half apart. I can make the windows shake and all the the hutch and on the walls vibrate in sympathy. My sub will cleanly produce the 16hz pedal tone in the Saint Sans symphony 'with organ'.

So, sheer low frequency output is not the deal maker. No, what you need is musicality. For movies? Why NOT replace the Bag End with another? That would be a real good place to start?