Have no experience with "greenfield" conduit. At one time I did directly wire 12ga. romex to my system power strip, bypassing the duplex - just to see if there was a difference in sound with and without the (regular) duplex. Indeed there was. Much better harmonics and overall sound without. Listened that way for a month or 2, but decided to choose an upgraded duplex due to the fact that if my house burned down for any reason the insurance co. would then have grounds to not honor the claim - even if the missing duplex itself was not found to be the cause of the fire.
But, in general, I've since come to understand that ALL connectors are, sound quality-wise, to be considered the spawn of satan...duplexes, light switches, dimmers, audio and video component connectors, speaker connectors, circuit breakers....wherever a wire is interrupted there is the potential for sound quality loss.
But, in general, I've since come to understand that ALL connectors are, sound quality-wise, to be considered the spawn of satan...duplexes, light switches, dimmers, audio and video component connectors, speaker connectors, circuit breakers....wherever a wire is interrupted there is the potential for sound quality loss.