Vandersteen 2w or 2wq's

the Q IF you can put filter between pre and amp or if your integrated as this feature.
spend some quality time at Vandersteen website
the FAQ section under support
The line level preserves amp transfer function and will result in better sound.
I had 3 A sig for many many years...
Personally I would flip them for a pair of used Model 5... there you get the better filters, much more capable subs, 11 band EQ, etc..
But I also understand the appeal of a $500 sub
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The 2Ws are pretty long in the tooth now.  Certain s/ns have had the amp upgraded. Check w RV. 

The 2W offers a somewhat "looser" sound which is intended more for the home theater crowd.  The 2Wq is more intended for use in a music system, the variable "q" allowing you to adjust the bass to your liking and more importantly, to the music.