I know that pioneer and Sony made some times with copper plating on the chassis, as did ..uhmm..Denon. Counterpoint, as well.
Lots of companies did this. Some have issued faceplates that were copper. coated copper, mostly, to avoid the oxidation issue.
I think symphonic line did some copper ones.
https://www.audiogon.com/listings/lis9199c-symphonic-line-kraft-400-monoblocks-with-internal-stealth...
Lots of companies did this. Some have issued faceplates that were copper. coated copper, mostly, to avoid the oxidation issue.
I think symphonic line did some copper ones.
https://www.audiogon.com/listings/lis9199c-symphonic-line-kraft-400-monoblocks-with-internal-stealth...