2020 Mac Mini (Intel) - Ground Loop Troubleshooting

[The Computer Audiophile]

I would start as simple as possible, then add components back into the system to find if a specific component is the cause. 
 

For example, only connect your amp and speakers. Is there a hum? Then move down the line. 
 

I did this once years ago and found the hum was related to my house ground wire. 

[The Computer Audiophile]

Oops. Just re-read your post. Forget my first suggestion. 

[The Computer Audiophile]

9 minutes ago, SkiTahoe said:

Appreciate the replies.  When I remove the HDMI cable from my Mac, the humming reduces slightly (or at least changes), but doesn't go a way completely.  Would any basic HDMI cable with that feature suffice?  

 

I've been researching some other options but I don't know if I'm misunderstanding the purpose of these products:

 

Jensen Iso-Max CI-2RR RCA Stereo Line Input Isolator Hum Eliminator -- Place in between my DAC and Amp?

Ifi Nano IGalvanic 3.0 -- Break the ground/power through the USB cable?

D/D converters (M2Tech, Denafrips, Matrix) -- Run AES/EBU or Digital Coaxial?

USB Regenerator (Intona, Uptone, SOtM) -- Clean up the USB signal?

 

It sounds like plenty of people use a Mac Mini as a source.  What's different or missing from my setup that might be causing the hum?  Thanks again.  

 

 

Yes, many people use Mac Minis and other computers without issues. 

 

You could try the very cheap and possibly temporary solution of putting tape over the power pin of the USB cable. This will isolate the power, but will only work if your DAC doesn't require power over this USB cable. 

 

Here's how to do it. 

 

[The Computer Audiophile]

I can’t believe I haven’t run into this yet. 
 

Looks like @barrows has grounded his Mac Mini. 
 

 

 

 

[The Computer Audiophile]

48 minutes ago, barrows said:

I grounded my Mac Mini (I have since moved on from it) by making a simple grounding cable which plugs into one of the unused USB jacks.  The cable just has a single 18 AWG wire, terminated to the USB "A" plug ground connection on one end, and a three pin AC cable on the other end with the wire terminated to the ground pin.  I was making a number of wiring changes at the time, so I cannot say whether this resulted in sound quality improvement, but from a technical perspective it  stops "high impedance" leakage currents from the internal SMPS from escaping. 

 

Similar to this, without the passthrough?

 

https://www.electrahealth.com/Premium-USB-Grounding-Adapter-for-Laptops-and-Other-Devices_p_159.html

 

 

[The Computer Audiophile]

or this

 

https://www.filteremf.com/buy/usb-ground-cord/