Another "kinda-newbie" head scratcher

Well that’s what I suspected. Glad you figured it out. 

Hello Eric!  If you have a Grado cartridge with a replaceable stylus (needle) the mount for the stylus actully completes a magnetic path and has a bit of magnetic cream on the edges of the mount that is easily scraped off in handeling the replacement. If that material is not intact, it can cause the problem you are experiencing. I speak from experience, but it was a very long time ago. Good Luck!

Does the volume control affect the loudness of the noise. If so, you may have defective components in the phono stage of the preamp.

@lewm 

RFI is also electromagnetic radiation, usually travels longer distances at high frequencies but is otherwise similar to EMI

Not really.  RFI is just a subset of frequencies within general EMI.  My favourite AI says:

EMI (Electromagnetic Interference) is the broad, general term for any electrical noise that disrupts a circuit, covering frequencies from 0 Hz up to several GHz (including power lines, motors, etc.). RFI (Radio Frequency Interference) is a specific subset of EMI, referring specifically to interference within the radio frequency spectrum, typically between 10 kHz and 300 GHz 

Currently enjoying vinyl "A Night In Tunisia" via Waxwing>digital coax>MSB dac.

No noise.

Simplest solution.

I will likely be selling two of my three phonostages.  1) Darlington Labs, 2) Sutherland, 3) Parasound