Remember the Dead Poets Society when Robin Williams told the kids to stand on their desks. To see the world from a different perspective. I don't even know if you all have put your boots on the ground. Wiring an AV room is not the same as wiring a 2 channel audio room. Proper grounding has little to do with the electrode in the earth. You don't use metal encased wire with a hot, neutral and ground. I don't care if its AC, MC or Steel/Aluminum pipe and wire. If you wrap you wire in metal you have to be very careful in how you do it. If you make a single mistake, you will have a very loud ground loop.
Many recording studio are wired with metal raceways. And many of those studio have a large isolation transformer that feeds everything. But the guy who designed the infrastructure is many times at the site during installation to oversee the project and make sure the electrician does it right. An electrician is your worst enemy when it comes to powering your audio system. They will ignore the spec and drawings, say they know best, then ask for a change order to remove and replace materials they installed incorrectly. Your much safer using NM.
And, you have to make a shop where you can limit variables and listen to what you preach. You have to go through 5 or 6 homes and step by step change out 1 variable at a time, then listen and learn. Let it sit for a couple weeks and get the owner feedback. Then go back and make 1 and only 1 change, then listen again and let it marinate. I have been fooled myself. I made a change to feeder ground and was all smitten with the resultant bass. The owner told me 3 days later to rip it out. It was all wrong. He could only turn the stereo on for about 1/2 an hour, then he was completely unsettled and turned it off. I changed it back and he said it was night and day better. He was back to listening for hours on end. I shared the experience with an industry professional and he explained why what we heard happened. WIRES HAVE A SOUND. Every one of them. Maybe your a denier and think every power cord sound the same. If that is the case, then why are you even arguing. It doesn't matter. If you do believe power cords have a voice, then why wouldn't 40 feet of wire in the wall also have a voice. Technical jargon is just that. Its indispensable to be educated, but you have to listen to what you do. I am constantly learning. I'm not perfect. I have made mistakes and stumbled. Like the ground above. But hey, the internet if full of people saying oversize your grounds. So I tried it. But every time I do experiment I know more. At times I go back to projects I did in the past and refine the installation to get a little more out of it. Like I said earlier, the NEC is a minimum. Just because it meets code, does not mean its anywhere near as good as it can be.
If you decide to put some holes in your walls and bring 5 or 6 different wires from your distribution panel out to your rack with the same termination on the end to listen, I would love to hear your impressions. I like to do this with my amp and my DAC. As well as phono preamp at times. And don't forget to let it rest in your system for a couple weeks. There is a big difference between back and forth listening and living with something for a while. What might sound WOW to you at the moment might end up quite grating over time. I find 24 hours or constant play with maybe 2 or 3 on off cycles is enough time to get a wire stabilized to hear what its doing.