I was playing an outdoor gig in North Texas last Saturday evening, and about halfway thru I lost what seemed to be about 50-75% of my volume level in my amp (Marshall AS100D, playing a Jumbo Takimine Acoustic). At first I thought it was my battery in my guitar's pickup, but I replaced it with no improvement. I then switched channels on my amp, also no improvement. I finished the gig with my vol levels for master and input way higher than I've ever played.
As we were packing up we all noticed there was significant dew moisture on all our gear, cases, etc. I then wondered if that was the source of my volume loss. I brought my equipment home and turned a low speed fan on it to dry out anything that might have built up inside the amp. I plugged everything in Sunday afternoon and it was much better that the night before, but not quite back at 100%. I also played a second guitar thru the amp that had not been outside the previous night, and there was no difference, so I do believe it is amp related.
Does anyone know what might have caused this?