Thanks for all the info. Surprisingly (to me), just twisting the tonearm cables together eliminated almost all noise. There's just a small hum when the volume is all the way up, but I would never listen to music that loud. Seems like the separate cables were acting as antennas, and the LFD phono amp doesn't have RF shielding. At least for the time being I've found a solution. Doesn't mean I won't try new cables - I'm an audiophile after all.
Thanks, Scott
Thanks, Scott