John Curl does not lift the AC mains safety equipment ground from the chassis on the JC 1 amp.
"TECHNICALLY SPEAKING", page 14
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"TECHNICALLY SPEAKING", page 14
3. Use the Ground switch on the JC 1 to eliminate most ground loops. This separates the JC 1’s signal input ground from its chassis ground to isolate unwanted voltage in the ground shield of the unbalanced (RCA) input cable. Be sure your system installation is finished before you try moving the Ground Lift switch from its “Normal” to its “Lift” position.https://parasound.com/pdfs/JC1Manual.pdf
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