"Ignorance is bliss."
in a nutshell, unless your CERTAIN your power feed's voltage is a +/- under 5% 120VAC, I urge you to consider a conditioner w/voltage regulation. My APC H15 SAVED my previous pre/pro from my former* home's electrical system. Further I believe the H15 doing the same for my (Same brand) current pre/pro.
*rental on a grid close to a lot of businesses & a junior college.
Even today** I witness the "Trim***" LED frequently light up on the H15 for several hours at a stretch several times a week. Because of "compromised" hearing****, I won't swear it "greatly improved" the SQ, but I'm VERY confident it's protecting my system's delicate microprocessor-containing components from the above and the brief effects from AC, freezer, & refrigerator etc startups.
**4 1/2 years in a rual neighborhood.
***circuitry activated when the line voltage exceeds 132VAC
****unprotected on tank ranges; 10th row seating at concerts; extended listening to insanely powered car audio systems - all when I was young & stupid
Your system's electrical "sweet spot" is 120VAC +/- 5V. Continue "Unprotected" at your peril.
Tony