For Vandersteen 2Wq users.

What he said :).

I would like to add that from my lengthy experience...The passive x-2 filters will change the sound of yours highs and mids in a negative way unfortunately. The active unit is the only way to go for transparency sakes...it is expensive but to me the vandy sub is almost worthless with the x-2 unless you have an extremely unrevealing system. If the active is too expensive then I would HIGHLY recommend to have a custom filter built with much better caps i.e. DYNAMICAPS,Auricaps,Cardas caps etc. I had one built with DYNAMICAPS and I can hardly hear the influence of the added connection...It sounds MUCH MORE natural and open against the X-2 and is very close the the performance of the active units at a fraction of the cost. Just trying to help from my experiences..good luck!

I totally agree with Aniwolfe. You must either make your filters out of a much higher grade cap or use the expensive Vandersteen model 5 crossover. The x-2 doesn't alter the frequency so much as it just isn't as transparent as it should be. It uses a relative low grade Rel cap. I have used Dynamicaps and also Auricaps. I found the Auricaps to be more to my liking but it is a individual thing. The filters are extremely easy to make. I probably have no fewer than 10 pair laying around.
With the Auricaps, I hear no influence to the mids and highs. I felt the Dynamicaps imparted a touch of brightness.

Let me "piggyback" on Bigtee's post. I have a stereo pair of 2Wq subs in my system (Vandy 3A Sig main speakers), and found that there was a noticeable improvement in overall sound quality when I replaced the regular ($125) crossover with the crossover units used with the Vandy Model 5. The M5 crossovers come in two boxes -- one for each channel -- and have much higher parts quality. In addition, the M5 crossovers also have an internal 9-volt battery that keeps the capacitors fully charged at all times. While the M5 crossovers are certainly not cheap ($600 for single-ended, and $800 for balanced), you can occasionally find a used pair for sale. The M5 crossovers are more transparent than the "standard issue" crossover, and also (to my ear) seem to provide a more seamless blend between the main speakers and the sub(s). Let me close by making a further pitch for a stereo pair of 2Wq's, rather than a single sub. There is a BIG performance improvement with the stereo pair.

This is interesting information that needs to be seriously considered. The Vandersteen has a great reputation, but it seems to be a bit on the demanding side to get it to sound its best. And when it comes to building or wiring anything for myself, well, I can burn water. How bad is that? My birthday is coming up soon and I have been wanting to give myself a subwoofer as a present. My choices are narrowed down to the Vandersteen and a Rel. The Rel may be the choice of someone how has less time or less experience with sound systems, but wants something musical.

Choices, choices, choices...