bat vk-51se vs. audio research ref2mkii

I have an X350.5 which replaced an X-350. I have a Ref2 MK1 and a Pass X.02 which I switch between. Both are fine preamps and both have their strong suits. The Ref2 is NOT noisy at all. it is dead quiet. The Pass is wonderful in providing every nuance of detail and has a deep and well defined bass. It is very tube like in many of its characteristics from a standpoint of sweetness, but the decay that the Ref2 demonstrates on violins and other string instruments makes it more musical if not more accurate for violin concertos or choral pieces. For rock and roll the Pass is my choice. Your decesion really rests on what your listening tastes are and not what an oscope would reveal.
Good luck,
Jeff

You are correct. The differences betqween the X-! and the X-02 are subtle. The difference between the X-350 and X-350.5 are substantial. I would try to find a way to get to audition one. I used to have Bat VK-60 monos along with the X-350 and I traded that BAT monos and don't miss them.
Jeff