VK-42 se? BAT for synergy or PASS?

I am looking at amps for a system consisting of a BAT VK42se pre and Focal micro utopia bes. Has anyone used something besides BAT with the VK42? The PASS in question is an x-250.5, feedback from those that have used these models would be most appreciated. Thanks.
I've heard a member had trouble with the gain of a VK-51SE with his pass x160.5. More specifically, setting the gain at 003 resulted in very high SPLs.
I would stick with BAT.