Vandersteen 4

Joshc, it sounds like you decided to keep your 3A Sigs. If additional bass was a reason to ask about the 4s, why not now consider a pair of Vandersteen subs? That would be far easier to implement and likely a better overall result.

I can't speak for Richard Vandersteen but it seems pretty reasonable that when he brought out a new model and called it the Quatro, he was simply trying to avoid confusion with the original 4. After all, the new model fell in line between the 3A and 5A but was significantly different from the old 4 and 4As.

Also, isn't it just a little ethnocentric to say he was avoiding the use of "4" because it might be considered unlucky in some cultures? Quatro equals four, it is only a matter of translation. ;-)

Back to the OP and other comments here. I don't know what the recent 4/4As sold for but the Quatro has been out long enough that used ones appear. Also, I would say a used pair of original 5s could be found for a reasonable price and that would certainly be a step up from the 3A Signatures.