Unless there is something not working properly in the preamp or amp, you'd have to assume that two Musical Fidelity products of the same product line should work fine together. You might want to try the MM/MC switch to see if it makes an improvement (but keep the volume down to start). It would probably help to know the make and model of your cartridge, and whether you're running balanced or RCA interconnects. Have you tried the preamp with a CD player or other, non-turntable, source to see if the problem exists for that source?