Advice on a preamp

I am looking to replace my preamp as part of my next upgrade(itis). I am currently using an Opera Consonance Reference50MkII tube pre into a Sanders Magtech Amp to drive Monitor Audio PL300 speakers (3 way, 4 ohm). Does anyone here have any good experiences with a particular preamp with the Magtech? I listen mainly to Classical, Jazz, Blues & Rock. Cheers