Clearaudio Accurate cart + Nighthawk Flight phono

My analog setup is SME 20/2 - Series V - Clearaudio Accurate cartridge.
I have just borrowed a Ray Samuels Nighthawk flight phono stage for possible purchase.
I am having problems with sound distortion, I have tried variations of Load and Gain with the Nighthawk, but cannot get rid of the distortion. I have the cart tracking at 2.2 grams. Is this a mismatch of cart to phono or have I got the arm setup wrong?