Why the fascination with subwoofers?

@mitch2 ,
I am glad you are considering the Vandy subs.
To me, they are the best way to add lower frequencies to a speaker- A simple 1st order crossover that eliminates frequency overlap and allows you amp to function at peak performance.
Once I sell my 2w and 2wq subs, I will be getting the new Sub 3 model.
Bob

@yogiboy ,
Vandies don't 'need' subs, but having them really fleshes things out, subtle but noticeable. Quatro's have built in subs with equalizer.
B

@brskie,
I own the non-CT Treos, and have 2 2wq subs. I am very happy with the combo. So much so, I will probably get the new Sub 3's when I sell the 2w's.
If it were me, first I would ask Johnny.
Barring that, I would think getting 2 Sub 3's with the Treo's might possibly be a smidge better than the Quatro's(as you can distribute the bass within the room)- Only if you have limited room/placement options-which is my problem.
The Treo's are a tad smaller than the Quatro's and I can place them easier in my cluttered LR/DR.
As far as amps go, the Pass should be a nice match. I have no experience with AR.
One thing I would offer is that Vandy's like zero feedback amps.
I use Ayre and Atma-Sphere.
Bob