OP,
If you are a believer of Cable and Amps, then your gear is resolving enough. With that said, and if your handy and good with soldering iron, then I think you should give the Speaker an upgrade. Just be sure you do not Frankenstein the Sonus faber
My piece of advice is to NOT change the component values, but change the crossover component parts brand, to say Mundorf, V-caps, Dueland and Jupiter. I get mine from partsconnection. It's easy to replace caps as you can read it, but for inductors, a bit harder specially if nothing is written on it. I have an Agilent LCR meter to measure inductance.
I have done this to my friends and my own home theater speakers (B&W and Klipsch) and I can tell you, i can here improve sonics and for the center speaker, a better dialog. So yes, just changing the brand of parts in the crossover can do wonders and its fun
again, YMMV