I have thousands of hours on my Nordost Heimdall2 power cables. And I put in new Gigawatt inwall wiring over 12 months ago, so hundreds if not thousands on that.
I now know I (and probably most audiophiles here) never had my power cables or power lines burned in, not even close. Because this cheap $300 product by Hagerman Audio Labs, the Frycroder2, has blown me away with only 18 hours on it so far.
A little box you just plug into the end of each power cable. It creates a series of oscillating waveforms, supposedly it burns in the power line all the way back to the first utility transformer.
Who knows if that's true, but already there is a large reduction in hash and grain, more black background e.t.c all the usual subtle things you get with burn in, but seemingly amplified 10x than normal.
I'm going to give each power cable at least 48hrs, so will take a 2 weeks to do and get a full picture after that, but already at this early stage I am a convert and Jim Hagerman is a genius.
https://www.haglabs.com/collections/break-in-devices/products/frycorder2-power-cord-burn-in-generator
