Vandersteen Sub woofers v Rythmik Subs


I really love the idea of the Vandersteen Subs where they are connected with the mains via extra speaker cable off right and left channels off the main amplifier, which is supposed to provide better bass transition from the mains while keeping the signature from the main amplifier. My question is with Vandersteen coming out with the SUB THREE and the price going significantly higher, I was wondering if there are other subs for less that you could integrate in the same way. (Most subs seem to rely on the line level input which is just a sub-woofer RCA going from the pre-amp to the amp on the sub). Can this same Vandersteen set-up be achieved with other subs?
I picked Rythmik since they are known (in the home theater community anyway) for being one of the best bang for the buck subs and the most "musical" of the bunch. (between Hsu, SVS, PSA).
And could I possibly achieve even greater sub-woofer nirvana since I could get an 18" for around $1500? Vandies only have 3 eight inchers.

I am a Vandersteen fanboy and I would like to support RV whenever I can, but don’t know much about my other sub-woofer options so looking for some feedback. Doesn’t even have to be related to Rythmik necessarily. If you know of other subs that can integrate the same way I want to know about it!

Thanks
bstatmeister
As far as what impedance to match the cross-overs at - I noticed that my amp has an impedance of 10k ohm for balanced connections. Does this mean that I should match up the WX-2 to 10K? I have heard that people often find that they get better results if they go one step lower. so in this case I would go to 7500K? Does the WX-2 go this low?

The WX-2 seems to be designed for single ended (RCA) only. In that configuration, you can select the 10k input impedance to start with and listen. It does have one lower position below 10k and that is 5k which is pretty much the limits for the WX-2. Make sure of your amps input impedance, because if you go accidentally to low, you can over tax the amp modules in the 2Wq sub. I had this conversation with Richard Vandersteen and got  quite the scolding for suggesting going to low on the impedance selection. He said his warranty would not cover this type of damage to the amp modules, so use caution and a low volume level to start with.
I, too, have an issue with my McCormack DNA-1 monoblocks, in that they have pretty low impedance-like yours.
Using balanced, I can only get to 22Kohms. And, I think going lower would be beneficial. So, either I go to unbalanced or have SMc Audio redo their work. I am leaving it for a time when I can reconfigure my wiring.
Until then, I still have the Atma MA-1's and Ayre MXR's, so I am in no hurry. (It's nice to have options).
Bob
MXR as spares..... :-)

first time I heard Model 7 was at RV’s house.... running on MXR...

( his amp was in development )

give that some thought.....
bstatmeister: "Honestly I would rather buy an extra sub than a cross over - at least to start off with...lol"

    I have no experience with the Vandersteen crossovers discussed but I'm fairly certain that having 2 subs rather than just a single sub in your system, provided both subs are properly positioned, would result in a more significant and obvious overall system performance improvement than utilizing a high quality crossover would.  You could always add the crossover subsequently if you thought there was a need.  

Tim