Is it possible for the 300 to overheat? Here's why I ask...

This weekend, I played at a neighborhood "Rocktoberfest" -- there were several other bands on the bill, with my band "headlining."  It was an outdoor gig, with a complicated stage setup, so to simplify things, I offered to let all the other bassists use my LowDown 300.  The show started around 1pm, with bands playing all day in the sunshine (temps were in the low 70sF).  The 300 performed like a champ all day -- every one of the other bassists remarked on how much they liked my amp (you'll probably sell a half dozen of them this week to the others that played it that day).  I was running the board for most of the day, and the direct-out sounded great through the PA.  The volume was set at around 5-6 all day (the amp was not on continuously -- it did get shut down in between bands), with no problems, including with the band immediately before mine -- I sat in with them and the amp sounded awesome.

But when my band took the stage, around 7pm, I plugged in and got nothing but nastiness -- farting digital-clipping distortion.  It sounded exactly like the noise I get when the battery on my Fender Deluxe Jazz bass dies, so I swapped out the battery for a new one, to no avail.  I tried a passive bass, and a new cable but nothing made a difference.  Tried all four of my presets and "manual mode" but still had the same problem.  I ended up having to use a DI box, and we had to shorten our set because of the time lost.

I brought the amp home, and the next morning, it worked perfectly (of course), with no sign of trouble.  I even left it on all day in my house, but it still sounded sweet.  The only thing I can think of is that some component overheated because of the long day outdoors.

I love my 300pro, and it almost never gets a workout like it did Saturday, but this experience shaken my confidence in the amp.

Any clues?

Thanks in advance for your help

PR