Sir, baka voltage ang fluctuating sa area mo. Just like sa area ko. Dati i don't use voltage regulators because i believe kinda a little bit sakal ang system ko. Although with high capacity regulators, kayang kaya kaso mahal. Residential pa yun place ko dati. But when i moved to a commercial place, there are times na nagiging 235v up ang voltage lalo na sa gabi so i HAD to use voltage regulators. Pero yun sub amp ko, directly plugged pa din.
If your keen on using a regulator, get the 2x power rating ng gear mo for headroom vs transient and peak load.