Just to provide a contrasting opinion, I demoed my Pass XA200.5 with the Joule LA300ME and it was a poor match in my opinion. The midrange was interesting for the first several hours, but then I found it cloying and boring. Plus, I lost the treble and bass extension, the dynamics, and clarity/transparency that I get with the BAT Rex. While I still wonder about the truly balanced and much greater power Joule LA450, the sound and build of the 300 definitely reduced my enthusiasm to pursue the next step up the line.
My opinion is that the BAT Rex is a winner with the Pass XA.5. I cannot speak to the VK52 or VK51 since I have no direct experience. I've read others who were disappointed by the Audio Research/Pass pairing, but never personally pursued the ARC Ref preamp line. Good luck.
My opinion is that the BAT Rex is a winner with the Pass XA.5. I cannot speak to the VK52 or VK51 since I have no direct experience. I've read others who were disappointed by the Audio Research/Pass pairing, but never personally pursued the ARC Ref preamp line. Good luck.