Dbid,
Steel is CONDUCTIVE, plastic is not. That means installing more than one electrical outlet within the wall box (say 2, 3, 4 or 6 gang), grounds are not connected through the walls of the box. If you don't understand why that is bad, there are countless threads here at Audiogon about dedicated lines, dedicated and/or preferential ground and isolated ground.
In addition to that, steel is magnetic and can contribute to the sound. This is why some designers of high end stereo gear use non magnetic chassis parts such as aluminum, copper and carbon fiber.
Steel is CONDUCTIVE, plastic is not. That means installing more than one electrical outlet within the wall box (say 2, 3, 4 or 6 gang), grounds are not connected through the walls of the box. If you don't understand why that is bad, there are countless threads here at Audiogon about dedicated lines, dedicated and/or preferential ground and isolated ground.
In addition to that, steel is magnetic and can contribute to the sound. This is why some designers of high end stereo gear use non magnetic chassis parts such as aluminum, copper and carbon fiber.