New electrical wiring specifications

Get a different electrician. 
Start turning off one circuit breaker at a time. 
 

@skyy92677,

Maybe a cable TV line, a ground loop isolator might fix that! See here

Mike

Personally at the distance you almost should consider a new 60 Amp subpanel in your listening room and very short runs to the receptacles.  I haven’t done the math in a while but I did ages ago for a workshop.  The 4 gauge wiring required for the 60A subpanel will outperform 10 gauge at higher loads, plus this way your ground and neutrals join together much more closely and are unable to develop a higher potential like you could with long, separate runs. 

@skyy92677  

At the suggestion from another user I bought the little red Amazon plug in circuit tester. It’s showing me I have 7 milliamps going  to ground, Google says this is quite bad. I turned off the all the breakers and that didn’t change anything it’s still 7ma. It’s so bad that when I turn the whole house surge on you can hear the toaster buzz!

That might have been me, but you are misreading that 7mA!! That’s the GFCI test level.  That is, if you are testing a GFCI protected outlet, and you press the TEST button you can expect 7mA to flow.  That’s very little, but any more and you can stop a heart. 

The important part of that test is to look at the AC and the N-E voltage.

Having said this, if you have  this hum occuring no matter where the gear is you may have DC.  If it’s happening only in the listening room the advice to disconnect any other copper wires like coax and Ethernet is valid.  

@skyy92677 Hum always occurs at the powerline frequency 50 or 60 Hz, depending on your national standard. Ground hum is always the result of an imperfect ground causing a resistance, and thus a current to flow. Induced hum is also due to an imbalanced induction of AC onto an otherwise unconnected wire pair.

This is why balanced inputs tend to be quieter - noise induced on both lines is cancelled by the inverting input. This is known as CMRR - Common Mode Rejection Ratio. Common mode rejection ratio is the measure of a device’s ability to reject the signal common to both the positive and negative device inputs, specifically, a differential op-amp. Fun Fact: The differential op-amp was invented 20 years before the transistor for use as a long distance telephony signal repeater. The patent was rejected for 10 years because the patent clerk didn't get how they could work, but was finally granted in 1938. 

So, now you know what you're looking for - either a grounding issue or an induced hum possibly by a wire pair closely adjacent to an AC line. Adding more grounding points is likely to cause more hum not less, and is a code violation. Double grounding, or grounding at multiple points in a system, can be hazardous and lead to safety issues. It can create parallel current paths, potentially leading to electrical shock hazards, fire risks, and damage to equipment due to circulating ground currents. I agree: find yourself a new electrician.