Sub question for my system

I run Thiel cs2.4's from a Parasound Halo A21. While the bass is very accurate sounding it doest have great low freq extension. I have an older M&K V125 subwoofer that has served me well in my HT setup and I'm thinking of trying it in with the Thiels in the 2 ch setup. I'll be using preouts from my preamp (both L and R channels) to the sub. My speakers are rated down th 37 hz or so, so where should I start with the crossover point on the sub? My concern is the M&K wont be musical enough to work with the Thiels, but im hoping that if its crossed over low enough then I might be able to get away with it. Failing that, and having to buy a more musical SW, and having a budget of $2k what are the better units to look at these days? Vandersteen is always good, but I'm open to suggestions. My room is 16x25 with 10 ft ceilings
Hi Last L,

I think the M&K is not up to the standard of the great Thiel 2.4 whic is an amazingly good speaker. i would run the sub in parallel, and probably cut if off around 45-49hz or music and around 52-55 for home theater with a pretty strong rolloff.

If you have $2K, that is a very good budget and on Audiogon, i like the Velodyne DD-series. Extremely easy to have very precise adjustments to blend...still would run in parallel. You have a big might just be able to get a DD-18 in your budget, the biggest one of the series besides the gargantuan 1812 signature (450 lbs!)...tremendous. Fast, tight, powerful and most importantly...very adjustable to blend in your room. Again, woudl still run the 2.4 in parallel and not use the internal crossover.

Good luck. my 2 cents.
The great sub in your price range is the Vandersteen 2Wq. Vandersteen, like Thiel, stresses time and phase coherence. The 2Wq will give you the kind of bass you get from Thiel, but more of it and more extended. Without stepping up to a Thiel or JL Audio sub, I doubt you'll do better than the Vandy. If you can manage it, go for the high-end crossover, the MHP-5 instead of the X-2 in-line filter.
One of the most musical subs you can get is REL. I have owned about 4 different models over the years. They sound amazing. I would never run a Velodyne for music. The Vandersteen subs I cannot speak on, I have not heard them. I would start aorund 60hz - 75hz and see what you like. The REL subs hookup a totally different way than most subs.
I just purchased the R-328 today. It has some similarities to the Vandersteen such as a hi level input that comes off the amps to help match the sound to the overall system. I hope is sounds as good people say!
My buddy has that same sub running with a pair of Dali MS4's... sounds great.