Subwoofer Decision


I have narrowed my search to two choices though I am sure I will get comments steering me away from these.
Contrast Rythmik Audio 12G with Vandersteen 2Wq. I would like to get only one though I know a pair are best choice. Could maybe afford 2 Rythmik, but only 1 Vandersteen for now. The subwoofer would support Dali Helicons (4 ohms) biwired and driven by 2 mono McIntosh MC 252's at 500 watts each into 4 ohms. Living room size aprox. 24'x16'x8' placement not centered on 16' wall due to furniture (wife) constraints must stay put. Subwoofer placement needs also to stay there as well, I know this limits possible best choice for placement, my bad. There is room behind, next to, and between speakers. Any help help is appreciated.
128x128lowfreqguy
I want to repeat my recommendation to use multiple small subs for a much smoother response. See here for an introduction:  http://www.acousticfrontiers.com/20101029using-multiple-subwoofers-to-improve-bass-the-welti-devanti... Good subs will sound better, but the room remains the real elephant in the room. In addition, I would never use subs without some room equalization such as the Antimode 8033. I am overjoyed with mine.

I have always used MK subwoofers. The originators and still right up with the best. Interestingly, they are not mentioned much.

 Vandersteens method of having a capacitor in line to roll off the low frequencies was also done very early in the Dahlquist DLP1 crossover.
In it you could change capacitors/resistors to suit your impedance and roll off frequency. Not sure if anyone else implemented a similar approach.
If you are at all handy with a soldering iron you could pop the top on your amp and install a pair of caps inline on the RCA + inputs. This would roll off your amp at a chosen frequency. Say 80Hz or so. Then your powered subs fed from your pre can  go down from there using their built in crossover. The crossover calculations are available online to determine the size of caps and (resistors) needed.
Vandersteen rolls off the entire frequency band, (via MIT caps in the pair I had) sends it to the subs and then has a boost circuit in the subs power amps to regain what was taken away, while the main speakers are then passively being fed (with roll off intact) thru the subs connections.
Works fine, just a different way.
Nowadays digital processing seems to be the preffered method via devices such as MiniDSP.
I think that bdp24 for has raised points that seal the deal for the Rythmik 12G  over Vandersteen 2wg as to the bass response and appropriate for jazz and fusion jazz (some R&B and little classical) which I listen to mostly. I am a bass player, both contrabass and electric bass (5 string mostly) and I need to hear those low frequencies well and strong. The frequency of low E is aprox 31 Hz and low C on contrabass with C extension (used mostly by classical bass players) is aprox. 33 Hz and low B on 5 string and 6 string basses aprox. 31 Hz, and low A on piano is 27.5 Hz. I need to hear these clearly and with authority therefore 2 Rythmik 12G-SEs should work well for me. This model has the paper cone driver. Looking for dealer in southern California Los Angeles county. Do these ever show up on Audiogon? I need to hear these but almost willing to buy on what I know now from responses here. I am investing in RTA and calibrated mic to help with placement. I now have authority to move sub to space for my basses and keyboard behind listening area in living room and in dining alcove a living room connected area making L shape to living room an extra 80 sq ft to living room. Really looking forward to new subs.