I played an outdoor gig tonight. Four-piece band - drums, bass, two amplified guitars. The venue's "house P.A." was three Bose L1 Compact PA units. We also had a box fan running, as well as strings of little LED lights above the stage. Power was supplied to the stage by one 50-foot cord, probably 14 gauge. About three songs in, the band leader tells me I should turn down, explaining that when I hit strong notes it made his amp sound bad due to voltage sag. I was playing through my Traynor SB12, and the BL was using a little Fishman acoustic amp. The other guitarist was using a 1000-watt class D powered speaker. I've been playing for over 50 years, and I've never been asked to turn down for this reason, even when we used Twin Reverbs and Ampeg V4s. So: Is this "voltage sag" a real thing, or bogus?