The stated budget of the OP is in the range 1500.00 dollars. You won’t find either of those Atma-Sphere preamplifiers anywhere near that price used. In particular a used MP-1 would be multiples of 1.5K dollars. Most responders are trying to recommend options that fit the stated price range. I’m very familiar with the MP-1. It is excellent sounding but in an entirely different cost bracket.
Charles
Charles