When I went to see a trumpet concert in a small setting I brought my dB meter. All the other people were holding up cell phones, I was holding up my dB meter!
Average levels were 85-95dB. A trumpet is one of the louder instruments.
At home I try to reproduce acoustic music and soft jazz at realistic live levels which I play at 80-85dB. I believe 75dB is the recommended number. For my birthday or New Years I sometimes just have to crank up some Led Zeppelin to 95-100dB for just a few songs. After awhile it doesn't sound that loud and you want to turn it up louder! Be careful!!
I am a semi professional drummer so obviously I know how live drums sound. Bass drum/Timpani 106dB, crash cymbal 113dB, toms 110dB, snare 120dB, snare with rimshot 125dB. Average dB 112-119db at the drummers seat. Other live instruments:
Normal piano 60-70dB, Fortissimo piano 84-103dB, flute 92dB, violin 82-92dB.