100v,115v versus 230v

We use 120 volts because Edison chose 110 volts DC for light bulbs. And that was because he couldn't figure out how to create bulbs running on 220 volts without burning out .

So the question really is, why doesn't Europe and the rest of the world use 120v?

Originally Europe was 120 V too, just like Japan and the US today. But in the 50's or 60's they were able to change to 220 V. It's an advantage because with increased voltage you get more power with less losses and voltage drop from the same copper wire diameter.

At the time the US also wanted to change but because of the cost involved to replace all electric appliances, they decided not to. The average US household already had a fridge, a washing-machine, etc., but not in Europe.

Excellent info ! an american scientist friend also shared this additional explanation to me example of Kettle and hot tubs,,,

110-Volt Hot Tubs

• Pros: Have a 110-volt power outlet? Score! If you’re in the United States and you’ve plugged any type of electrical device into a wall outlet then you have the necessary socket to run a 110-volt hot tub. So, just fill with water, add your hot tub chemicals, and enjoy!

• Cons: What’s 220 divided by 110? No need to bust out that calculator; the answer is ‘2’ and that means it will take twice as long to heat up a 110-volt hot tub as it will to thermalize a 220-volt hot tub. To add further insult to injury, the amount of time your pump runs to circulate the water will also double (compared to a pump in a 220-volt system).

Questions remains, if 220 volt has more guts and torque does High end equipments sounds better at 220/230 volt ?

Audio gear such as amps, preamps, tuners, CD players etc typically have transformers inside. Whatever the line in voltage is, that line in voltage is changed to whatever the component actually runs on 

"To add further insult to injury, the amount of time your pump runs to circulate the water will also double (compared to a pump in a 220-volt system)."     WRONG!   The typical, dual voltage, AC(single phase) electric motor, when attached to a pump, runs at the exact same RPM and HP (https://spicerparts.com/calculators/horsepower-torque-calculator), wired for either voltage.      The only thing that will change, is the current draw, which will drop by half, at the higher voltage.      ie: https://www.youtube.com/watch?reload=9&v=3llc68VvzsY     Notice here, that though the motors are all dual voltage; only one RPM is mentioned for all and one HP rating for each, in the specs: https://www.poolblu.com/Public/pbsShowFamily.aspx?xFM=FM043298&xCT=