Hi Sean,
As everyone else said here, start at 100 ohms. I found that the MC carts of the last decade like to be loaded as high as 500 ohms, some even at 1K. It all depends on and boils down to what the system calls for, your taste, and the tonal spectral balance you are after. Afterall, audiophilia is a crazy and personal thing. I strive for a balanced, neutral and natural balance, out of the way of music with all my systems. Make sure you give those settings/resistors a bit of time to break-in before you decide that one choice is definite. I've been in this hobby for 25 years, designed and built electronics. I hope this helps.
Best regards,
Dan
