I purchased the supernait 3 from another user. When turning on, there is not ahum/buzzing noise. As soon as I plug in the rca cable from my RME DAC to any input (stream, phono, etc.) the hum/buzzing starts.
Question: does it mean I could plug in one end to the Ground input in the back of the Supernait 3 and the other end to the power strip that I have the DAC and the supernait 3 plugged in?
Assuming it’s only the RME connected to the SN3, I suspect the RME uses a switching supply which can give issues with Naim amps. You want to create a connection to mains earth from signal ground. You could do that via a mains plug earth pin to the ground connection (signal ground) on the back of the SN3 as per the quoted post.
Alternatively just take a length of wire and connect it between the ground connection on the SN3 and loop it around the outer metal shell of one of the DIN sockets. The DIN sockets are mounted to the case and this is connected to mains earth. Saves messing about with mains plugs.
An off cut of cable will be fine. Just strip off the insulation and loop the bare copper wire around the DIN socket. Strip the other end and attach it to the ground post. See below (using my NDX2 DIN output for illustration).
Much appreciated James! I bought a 20 gauge copper wire from a local store and that indeed does solve the hum. I was for a moment there thought he sold me a bad amp.