Clean ground

@Pauly- so is it safe to say that nothing in the audio system plugs into a wall receptacle for the household electrical system, but instead, the entire system is battery driven? Apart from the system that charges it (which is connected to your electrical system, I presume). I wonder how this would be treated under the applicable electrical code since if my assumptions above are correct, none of the system components are "plugged in" to the household system.
@Jea48 might have some insight, which is the only reason I’m tagging him-- I’m sure he has other things that occupy him too. Interesting question. I have a battery powered line stage with tubes that is a marvelous sounding beast.

You asked: "Is your bus at the copper colored bar towards the left rear? That would be great. I need one that’s not connected to the house main ground, but a second dedicated for audio ground. "
Yes, it is blurry, the focus was on the phono stage sitting in front, but that's a standard copper buss bar that I adapted with some generic fittings to mount on the wall. And the 4 gauge cable (you can see where it attaches to the bar) runs back through the house down to where the electrical sub-system with big Iso-transformer are stationed. I had commercial electricians do the work. It was worth it. 

@whart

Correct.Nothing touches a wall socket with the exception of the three prong plug that provides access to ground.

I charge when I’m not listening.

In the rare event that I want to take input from, or output to, a device that is plugged in on a wall socket, I use an audio engine Bluetooth connection. There is never a physical connection between components on battery and components on mains.

If you have a better pic of that there busbar I’d like to see it. Even focused images seem blurry to me so your pic is challenging.
Thanks

Pauly- here's an example, I think you can get these cheaper and they are sold on Amazon as well.
I will also try to take a photo of my set up that better shows the bar and post it later. In the meantime, here's the commercial site. 

Great thanks. The McMaster-Carr site has given me a good idea what they look like.

Are you familiar with a marine DCV grounding system? It's based on a star hub grounding system. When you dock you can ground your star hub to the docks ground.. or in your case a new copper ground rod driven in the earth. It has to be completely separate from the house earthen ground.. Your battery charging system is the issue but only when charging..

Every device needs a - and + to work, all devices - are tied together on the star, and the star to the - side of the battery. The + side is the fuse side. The closer to the battery the better.  Use a GREAT automotive or marine fuse bus it makes a big difference in SQ.. Each battery driven component gets it's own fuse..  All battery connections are treated with NoCo. It's a battery terminal contact enhancer and soft sealer..

I've done a few pleasure boat installs.. It's close as long as there is not an onboard AC genset.. Deep cycle DC sound systems can ROCK.

Regards