[DMcMahon]

A large number of R2Rs only come (as built) with 2 core mains flex/cable, particularly from continental Europe, the majority of these are not double insulated.

Where practical I always convert to 3 core mains cable and connect the earth wire to the chassis metalwork and of course convert the often fitted 2 pin plugs to UK 3 pin.

This is for my own peace of mind safety wise, particularly as I do a lot of live working inside them (live working only suitable if one is competent and then only with extreme care).

The only exception to this, to my mind would be on the very ancient and rare recorders that have a live chassis, I have never seen one but have heard of a few.

My 6000X (model 6021X) actually came with a 3 core mains cable with the earth connected to chassis metalwork, so presumably done by a previous owner. Have never experienced earth loop hum with any 2 to 3 core converted R2R.

I personally would strongly recommend earthing it and would be surprised if you subsequently have a hum problem.

Update - And check that the earth wire does internally connect to chassis metalwork.

David