I had two amp surprises, a bad surprise and a good one. One was the Eden WT. I wanted big fat tube and I got clean hifi tube. Barf.
My other surprise was playing for free, for about 200 people in this giant hand-built barn out in a commune. We were told amps would be there. Mine was... a pignose! Drummer had a full birch kit and he was a loud player too. I bitched and moaned before we started and was ready to basically play air bass for our 2 sets. Thing is, we were on a large, high wooden stage, a big resonant cube of lumber, and the pignose was sitting right on it. It wasn't an 8x10, but with that chamber beneath, the pignose got the job done! I was amazed. After that I totally got why engineers sometimes lift an amp off the stage.