You need to worry about digital noise far, far more than AC Main voltage as it changes a lot from hour to hour. I am not sure what the thinking is for a higher line voltage, since it is limited to VA by the transformer and you can't get something for nothing. That is, if you boost line voltage by 10% you drop current capacity by 10% and that assume the transformer is 100% efficient, which they never are. A drop in current capacity increases the likelihood of a voltage sag.
Keep the digital stuff isolated from the analog stuff. If the power amps drop the line a bit during a immensely massive surge, the power supplies in the other analog stuff will compensate okay. Remember the AC Mains can provide 1800+ Watts, average, to your equipment. There is nothing in music that is going to cause that to sag. Refrigeration, electric stoves, heaters, that big stuff will cause a line sag but you should have your equipment on a separate circuit from that stuff.
Keep the digital stuff isolated from the analog stuff. If the power amps drop the line a bit during a immensely massive surge, the power supplies in the other analog stuff will compensate okay. Remember the AC Mains can provide 1800+ Watts, average, to your equipment. There is nothing in music that is going to cause that to sag. Refrigeration, electric stoves, heaters, that big stuff will cause a line sag but you should have your equipment on a separate circuit from that stuff.