((In the future I might add a tight sub, maybe a REL. But mostly (90%) I
am very happy with them. They are very musical, and I don't have a high
$$ system.))
Glad you are happy,
Adding a Rel to what you have will only bloat things.
What you should do is ask your Vandersteen dealer to try the X2 assessment unit.
High Pass into your amp start at the lowest setting listen and work up until you achieve the bass you like. you can then order the fixed x 2 that you like and then later add in a Vandersten 2WQ or 2 this will provide a far better in room response by relieving any amps burden improving dynamics clarity and transparency in the whole system .
Best JohnnyR
Vandy Dealer
