Always worth having a backup. At Rebellion in 2019 I plugged into the provided - and obligatory - Ampeg SVT, got levels etc, all good.
Waited til we were ready to go, got the go signal, turned up the volume on my bass, hit a note just to make sure, nothing.
Luckily there was a spare SVT behind the stack. I could have DI’d via my Para Driver no problem, but just shows, a bit of gear can fail at any time.