faust168
The A47 has a very low 20k input impedance, suggest you stay away from tube preamps, one because they can be an impedance mismatch, two they are also capacitor coupled, and if that capacitor is not big enough it could roll the bass off too early.
My suggestion is to go with a direct coupled solid state preamp, maybe the Ayre’s K1XE, I would ask Charlie Hansen (Ayre) if it’s direct coupled.
Cheers George