The best way to explain it is to use the example of really large voltages. Insulators are used on overhead distribution lines to prevent voltage (pressure) from jumping from high to low (hot to ground). The higher the voltage, the larger the insulators. This principal applies at 12kV or 12V.
in homes, the weak spot/link is the outlet?
One of them, yes. 240V would be more prone (more pressure) to arc than 120V. Think of it as keeping the dam from bursting.
damnâŚ
would high powered amps be most at risk? (sometimes logic doesnât prevail, so i ask this stupid question)
(and thanks for info guys!)
Not being an EE in simplistic terms I just think of the Amps as the size of the hose (volume) and the Volts as how far it will spray (pressure) 
Just to take the thought to extremes I have 14,400 volt 3 phase supply coming down my driveway at the shop. The hi voltage leads have 20 amp fuses going to the transformer that supplies me with 1000 amps of 240 volt service. I think the wires going from the 14,400 volt lines to the transformer input fuses are 10 or 12 gage bare wires. The 240 volt lines coming into the shop from the transformer secondary side look like 3/4" garden hoses.
At 14,000 volts, it takes a very small amount of amps (garden hose) to have enormous power. Watts or power is equal to volts (pressure) x amps (garden hose). Therefore your smaller garden hose with the higher voltage. You can power more stuff with a 240voltage, with the same 20 amp circuit than you can with 120volts. Iâve work in buildings with 277/480v power and we could power many more lights than a regular 120/240v on the same 20 amp circuit.
so the 240v would have more âheadroomâ for amps?
No, because the transformer will step it down to the voltage that the circuits requires so it doesnât matter if itâs 120v or 240v.
The 240V is only the input voltage. As already mentioned, the internal transformer steps down the voltage to what the internal circuitry wants to see.
As to arcing, a great example is static electricity. It leaps from your fingertips to any ground as it is high voltage, around 25,000 volts. But the amperage is low so it is only mildly annoying.
Hopefully this is close enough on topic, but for those of you have had 20A direct lines installed, how much was it? Was it an all in fee, per foot or per hour charge? What were your materials cost? Did you source yourself or did the contractor supply everything?
Just trying to understand whet a good deal looks like when I call for quotes.
You should be able to get a residential electrician to give you a fixed price quote. I would expect the cost to be less than $1000 all in. If you are in a small town or rural area the price will be lower than in a big town.
I did my runs myself so the only cost was material.
Other problems are currently intervening in this for me that are probably going slow this all down. See my latest post in the ask the experts category. Fedex is not exactly on my favored list at the moment. Or not; I guess I could still pursue this, even though I donât have the pair of monoblocks on hand.
Short runs can be $500 or less. Longer runs that have to be fished through ceiling joists can incur costs from other contractors to fix holes.
yep, bang on. My 20amp dedicated line cost $400 all in. the line was fished through the ceiling and dropped inside the wall near my rack - about 40 feet away. Awesome contractor and probably took less than one hour.
I have a duplex outlet. The line is feeding a P10.
I had 3 dedicated 20amp lines added to my listening room for under $700, if memory serves. They were able to run them through the basement and the whole process took maybe an hour.
Recently upgraded a dedicated 15 amp line with common 10 ga and
Shunyata outlet serving a P20. Replaced it with 20 amp breaker,
DH Labs 10 ga âpure copperâ wall wire, Synergistic Research outlet and
SR carbon wall plate. To my ear, no difference. 
Did you switch to a 20amp power cord?
Dedicated is the key, the rest doesnât matter as muchâŚ
Good point. Yes, there is a Shunyata Sigma 20 amp cord to the P20.