GTT Audio in NJ, talk to Bill, a great guy who really knows the loudspeakers well.
I believe Rhapsody in NYC is an Avantgarde dealer.
Best system I ever had was Avantgarde Trios (with bass modules) and Lamm electronics (L2 Reference Preamp, ML2.1 Amps, LP2 Deluxe Phono) wired with Transparent Reference XL.
You're in for a life-changing experience.
For what it's worth, though I've never used GTT, that's where I'll head when I return to Avantgardes. Bill Parish is supposed to be a really good guy. Happy listening --