I'll freely admit I don't fully understand all of this but the bottom line was Rzyard used a two prong adapter and the noise stopped. I did the same thing and the noise stopped. My interface is a Sonic Cell with a USB connection. I have several other devices plugged into that power strip like my mixer, my 32" HD TV and a couple of other things that use a regular heavy three prong AC cable. As long as that remains the case Mac says that is fine, I'm protected so I don't see where the USB cable comes into this either with my setup or Rzyards's. There's still plenty of ground protection coming through the fully grounded 110v AC from the other devices.

Bob


Biab/RB latest build, Win 11 Pro, Ryzen 5 5600 G, 512 Gig SSD, 16 Gigs Ram, Steinberg UR22 MkII, Roland Sonic Cell, Kurzweil PC3, Hammond SK1, Korg PA3XPro, Garritan JABB, Hypercanvas, Sampletank 3, more.