I just did a quick test, adding a low cost subwoofer to my old Pierre-Etienne Leon M1 speakers, and it made quite a difference.
If I could find a matching center, I would consider the option of keeping them and add a sub and surrounds.
Twoears, I've not heard of those speakers you have but that is an option you might consider...ordering a centre channel, and trying it out. Axiom gives you 30 days to trial the speakers, if you feel they don't match...you just pay shipping to send them back. Perhaps one of the guys who has Axioms near you would let you hear your speakers with their centre?
How would you describe "the perfect sound" that you are looking for? Do you like a warmer or 'laid back' sound? a more forward, detailed sound? certain speaker co's have certain traits or characteristics in their products. Companies like Axiom, Paradigm, Monitor Audio, B&W, Kef and Klipsh to name a few, have somewhat similar approach to sound.
