(pyramid xpa-240)if i had 10 voltage extra to a amplifiers what will happen?
By law, for safety, the voltage and power specs are near the AC power entry.

Notice the protected slide switch says 115 or 230V nom.  Just use the correct position and your expected difference input is less than the usual 10% tolerance. (+-23V)  It would only mean a slight increase in surge current when powering on.  

If you experience frequent power interruptions from poor power quality in your area, perhaps some protection could be added like MOV found on most power bars for surge voltage and maybe consider adding an ICL for inrush current limiter.  (guestimate 10A)