120v vs 240v

All US panels are already 240V, so there is no need to change a panel, unless you are doing a whole lot more than adding a couple amps. I had no problem adding 9 bitcoin miners to mine, and that was a continuous 70A load. Continuous. Cannot even imagine what one would need to do to actually need a bigger or upgraded panel. Even if more circuits are needed you simply buy a breaker called a thin twin that lets you put two 120V circuits in the same space as would normally be for just one. But whatever. If past experience is anything to go by it is unlikely anyone determined to spend money unnecessarily will be dissuaded. Hire an electrician and go for it.

When considering all the advice you will be getting, including from electricians, you might want to consider I have experience actually doing all this stuff. https://systems.audiogon.com/systems/8367 That’s a 240V to 120V Audio Consulting step down transformer you’re looking at there.

The advantage of 240V is power. Watts are power and voltage (pressure) times amps (current flow) equals power in watts. So the greater the voltage the greater the power. What this means in practical terms is faster charging of the amplifiers power supply caps. Amp power ultimately comes from the amps power supply, not the wall. But the caps are constantly being drained and topped off, and the faster the topping off the more dynamic the amp will sound.

That anyway is the theory. Whether it works or not is another thing altogether. Me personally, having tried and compared it several different ways, no way you would ever get me to run more than one line to a room. No matter how much money you gave me. And absolute last thing in the world would be to use more than one line and a bunch of dedicated grounds.

But hey, don’t take my word for it. Listen to Mikey. Skip to 15:50.
https://ultimist.com/video/2018/07/21/michael-fremers-listening-room/

Bitcoin miners? 9 at 70amps! Dude, you are the most interesting man in the world.

You could run one 8 gauge 240v run to a sub panel at the equipment location and divvy out what you need from that. You'll then have twice the current capacity when broken out as 110v without needing to run thicker cables from the main panel.

Do not buy the thin twin breakers until you check the local code. In RI, they are NOT allowed. It does put unnecessary stress on the spot in the panel. I am amazed at some of the things people do with their panel and running new circuits. Anyone ever hear of electrical fire?

Two weeks after we moved into our present home in 1994, we had an electrical fire. Had I not been in the basement at the time and a fire extinguisher close by, I would have lost the house. Flames were shooting out of the panel!  The entire panel was toast and the wire burned on the outside of the house, all the way to the connection from pole to house. The cause was a secondary panel the original home owner added to the main panel. The wires were very loose and we all know a loose wire causes resistance which produces heat. We were very lucky. I had to spring for a new service which I had upgraded to 200 amps from 100 amps. We couldn’t live in the house for a month until it was cleaned up from the smoke damage and new service installed.  My insurance company had a 40 foot trailer delivered to our driveway which we lived in while the repairs were made.  Oh, my insurance premium almost doubled after that fiasco. 

240 volts allows for smaller wire sizes since the amperage draw is cut in half for a given amplifier power consumption rating at 120V. Since you are using #8 wires you are negating the main advantage going to 240V.