Any question answered...

That's a bit odd unless it's the vibration from the audio that's causing the earth cable to loosen?
Sounds more like imminent amplifier explosion... kidding.

Probably not, since the impedance of the transformers won't be matched to a record pick up. Sorting out your intermittent grounding problem would be best, and should not be rocket science with a Dual-Rotel set up, but there are different ground loop isolators available for moving magnet and moving coil pick ups.

A sliver of emery board rolled into a tiny tube, cleaned out the spade connectors to the cartridge, and woot! All is hum free ... sooooo happy!