"You need a random source close to 60hz" Correct. I specified a Zener diode source coupled to an oscillator. This would provide the signal noise filtering and

"You need a random source close to 60hz" Correct. I specified a Zener diode source coupled to an oscillator. This would provide the signal noise filtering and phase-locked-loop (e.g. the necessary +- ppm signal power spectral distribution control). Given propagation losses, my ENF signal doesn't have to be nearly as powerful--merely more closely coupled to the device(s) being "shielded". Also, I think a so-called fast-switching DC-to-DC converter would provide the necessary isolation. Plenty are being manufactured now that isolate down to 40Hz, but outside of the audiophile realm, that quality of filtering isn't typically used for low-power applications.