EAR 834P Deluxe with Dynavector 20 HX H output Cart.

I am using the High output MC Cart. and have to use in MM setting on the EAR. Someone at a shop said if I use a Dynavector 20X low output that I would have to turn my volume on my pre-amp too high. It seems low would be the right choice being in MC mode I get distortion with my High Output Cart now? Can anyone help with this situation?

Thanks very much!