Slight buzz through speakers

Hello @straightwire and thanks so much for taking the time to send such a thorough and detailed reply😀!

I currently have Comcast/Xfinity. Unfortunately, Verizon FIOS is not available in my area and because of my location (lots of woods/tall trees) satellite dish is not available either. It's Comcast or none. I already tackled the cable box buzz as it was very loud and went louder as volume was turned up. Unplugged the coax and hum disappeared completely. I bought a coax hum eliminator and once installed no more buzz/humm whatsoever (this was when I had my previous Marantz AV8802A as my processor). Soon as I upgraded to the Mac and reconnected a very faint buzz could be heard. I started with cable again disconnecting and hum still there. One by one I disconnected and reconnected every component in the system. Buzz never went away. The volume of the buzz has stayed consistent never changing with volume or anything else...

Once I tried unplugging my XLR cables leaving only the Mac and my Sim amp (with speaker cables connected to my amp) connected buzzing went away. As I reconnected the XLR cables 1 at a time the buzz returned to that speaker/channel. At this point it seems (unlike the Marantz/Sim combo) like the Mac and Sim just "do not play well together". There's only 1 other thing I haven't tried and that's going RCA instead of XLR. But I have spent a very small fortune on my Transparent XLR's so that's not really an attractive option-though I will try to see if that takes away the buzz just for kicks as I have a few RCA's hanging around. So I'll try just to see if that changes anything.

The only other thing I can think of is that whilst I never had this issue with my Marantz, the Marantz is a 2 prong plug and the Mac is a 3 prong. Maybe somehow this makes a difference? Though I did try a cheater plug on the Mac and the buzz was still there...

I have had many folks reach out and tell me they have the same issue and that because it's so faint and can only be heard ear within 2 inches of the tweeters, do not worry about it at all. So, I'm starting to wrap my brain around it🙄, It cannot be heard at all away from the tweeter and from any listening position and is not intrusive at all (other than my OCD knowing it's there) so I can certainly live with it. Besides I have tried pretty much everything...except calling in a priest to get rid of this evil entity but I've seen the mess that makes afterward😂🤣

Thanks again for the thoughtful reply...I'm still open to any/all suggestions...

The RCA cables are worth a try, but I doubt that will make a difference.

The third prong in the plug is the ’ground’ which can pick up RFI. This can be defeated with a two prong plug converter.

Sometimes there is a hum in standby, but it clears up when content is played.

If the McIntosh has a noisy transformer, nothing will eliminate the hum. Try putting your ear to the unit while it is turned on, with no content playing in a very quiet room. Better yet, if you have access to a good stethescope, use the stethescope to listen for hum coming from the unit. If you hear a slight hum coming from the unit, it has a noisy transformer. If that’s the case, they are probably all made that way.

If you like the new McIntosh better than your old Marantz, try calling Marantz technical support for additional ideas. With or without hum, it should out-perform the old Marantz by a significant margin to justify the cost.

Thanks again @straightwire. I did try the 2 prong cheater plug and the hum was still there. There is no noise coming from the Mac unit itself, but through the speakers. I am pretty convinced that somehow introducing the Mac with it's 3 prong plug somehow opened the gateway and allowed this entity to get in.

You are definitely correct this unit is a definite upgrade from the Marantz, and I have called Mac's Tech Support. But they really couldn't diagnose, everything they suggested I had already tried... I guess this unit like others have said "just doesn't ply nicely with others". At this point I am learning to accept it. It is by no means intrusive, and you cannot hear it when music is playing (though with ear to tweet and low volume I can hear it but that's because I'm listening for it too). But when volume is at normal levels you cannot hear it at all. It is very faint so I guess in some ways I should feel lucky (others have said this as well) because this is so common and much worse in many cases...