Cartridge Impedance


I just bought a phono pre-amp that allows me to adjust the impedance of a MC cartridge. I was using 100ohms. Now I want to experiment.
Could someone tell me the effect the trebles will have if I lower or raise the suggested impedance. For example, If I raise the impedance will the highs be more prominent or less prominent? 
Thank you.
jmh128

Showing 1 response by stereo5

Changing the impedance from 100 to 200 ohms with my Denon moving coil increased the clarity and focus and the highs sound better.