I had a similar situation where the venue over-booked and had to put people in two different rooms. I played the big room to about 280 ppl...and they insisted I tap into a house system that ran into a smaller lounge of 80 ppl.

My mixer distributed the signal to both my Bose L1 and their system. In the the big room it was fine. In the small room it was a nightmare. People from that room would come to me and tell me it was way too loud....or not loud enough. I couldn't hear what they were hearing so could not adjust it remotely. The amp for the speakers in the small room were behind the bar and nobody seemed to know how to work it. Nobody complained about distortion in the small room, but I can't believe the 5" ceiling speakers in the small lounge were not distorting.

Neither the venue or the audience blamed me because I advised against doing it in the first place. But, the venue had a lot of disappointed and unhappy customers that night.
Eddie