What voltage to run my gear...110V or 120V or something in between?

So recently my Accustic Arts integrated amp died.  According to the tech that fixed it, the regulator and rectifiers failed.  This got me thinking that perhaps I have the output voltage from my PS Audio P3 AC Regenerator set too high?  I've always had it set to 120V but can reduce it to as low as 104V.  I know that most devices we can plug into the wall should be able to handle 110-120V plus or minus 5-10%.  However, I wonder if by setting my P3 to 120V it may have lead to me prematurely damaging it?  

Any thoughts would be appreciated.