VTA is the first thing I would check. Raise the tonearm by several millimeters and see if that improves things.
Ortofon recommends an input load impedance greater than 20 Ohms. 100 Ohms should be fine. But if you want to try 20, you can make RCA cheater plugs with either a 27 or a 33 Ohm resistor wired in parallel.
Ortofon recommends an input load impedance greater than 20 Ohms. 100 Ohms should be fine. But if you want to try 20, you can make RCA cheater plugs with either a 27 or a 33 Ohm resistor wired in parallel.