You can call lone mountain audio, the us distributer. They have always been informative and helpful. I purchased used ATC 50 active towers from my audio acoustics vendor (Acoustic Frontiers) and bought a used ATC center C6CA directly from loan mountain ( also through my vendor). I had a really hard time finding a place to audition the ATCs but finally found a local store that was able to source one from ATC that was at an audio show. I didn’t want to put down the big bucks for this without ever hearing them. Actually, I take that back. While vacationing in London I went to a local hifi shop that carried atc. It was a passive version of one of the lower models. It was fine but I wasn’t blown away by them. I waited til I finally got to hear the model I wanted to buy.