Best preamps for phonostage performance?

Seems to me you need a preamp with balanced outputs to work with that amplifier.

You might be able to find one of our MP-3 preamps used for that price. The MP-3 is all-tube, fully differential and balanced from phono input to main output.

If vacuum tubes aren't an important factor, the field widens but these days its a bit of a trick to find a preamp with the phono section built-in.

Just about any version of the CAT SL-1 has a great phono stage but they only have unbalanced connections and need A cartridge with at least .03 output unless you add a SUT.