120v vs 240v

240 Volts!Thin end of the wedge there.Next thing you know you will want us to give up our military style weapons and left handed fishing reels!

cleeds my bad your right my mistake they have 20amp breakers 10/3 wire is 30 amp i have 10/3 wire 

ditusa

CLEEDS the the plug that is needed is a leviton 5842-i i have 2 in my home in stall by a electrician 125v 20amps top bottom 250v 20amps ...

That’s fine, but the circuit you described was 30A for both the 120VAC and 240VAC lines. That Leviton receptacle definitely doesn’t meet my local code for that purpose and I don’t think it meets NEC, either.

i get it go on amazon type in leviton 5842-i  plug i went down this road if you do run #3-10 awg from pannel to plug now you can run any thing from 100v to 250v consult a electrician tell what you want

Clarification 
perhaps my prior post was a bit inartfully stated

i am trying to accommodate future potential needs while addressing present and future costs.  I have no issues changing out breakers and plugs in the future to accommodate a potential 240 v amp., as last ng as the wiring and ground are adequate Definitely doing a new panel as I am adding 2 Tesla supercharger circuits, summer kitchen etc

No change of the amp is needed

Depends on the amplifier. 

DJONES he wants to know if runing the amp on 230v will sound better yes it will i my amps and preamp run on 230v i went down that road no power cord will do that

CLEEDS the the plug that is needed is a leviton 5842-i i have 2 in my home in stall by a electrician 125v 20amps top bottom 250v 20amps my amps run on 230v to run 125v change the power cord thats it 230v powe cord is a nema-6-20p to c13 iec my amps see the voltage from 100v to 250v no change of the amp is needed

Consult an electrician to get advice based on the codes in your area. I can't figure out what you're trying to do. Figure out if you want 240v amplifiers or 120v first. 

ditusa6

I would recommend 2 30amp dedicated circuits using #3 10 gauge wire. With both receptacles will be dual voltage: top plug 125 volts 30 amps and bottom 250 volts 30 amps ...

That’s problematic for several reasons. First, you’ll likely need to use a special receptacle for that 120VAC 30A line, because many local codes won’t allow a conventional 15A or 20A receptacle on a 30A line. So the receptacle you’ll be using won’t be compatible with the plugs on your equipment.

The 240VAC 30A line will also require a properly rated receptacle. Again, that likely won’t be compatible with the equipment’s existing male AC plugs.

And you are not going to find a duplex receptacle - which is what you’re describing when you refer to a "top plug" and a bottom plug - with different configurations between the two plugs.

 I would recommend 2 30amp dedicated circuits using #3 10 gauge wire.  With both receptacles will be dual voltage: top plug 125 volts 30 amps and bottom 250 volts 30 amps...running the amps on 230 volts increases the dynamics of the amp, transient response, and lowers the noise flow.  No speaker cable I ever tried made that difference... 
just a thought... 

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.

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. 

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.

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

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/