I always bring two basses to a gig and have done so for many, many years. The one time I did not bring a second bass was a local gig at Yoshi's in Oakland. Soundcheck went well but when we walked out on stage to start the set there was no sound coming from my Modulus. Naturally I freaked out and after reinserting the cord a number of times the bass came back to life and made it through the show. The next day I opened up the bass and realized that a solder joint on the input jack had failed, the wire was barely touching, I was surprised the bass had made it through the show and even more surprised that the sound was clean, not distorted. Easy enough repair but it was a reminder to never put myself in that position again. I usually leave my primary instrument on stage after sound check so it stays acclimated to the temperature in the venue and warm up on the spare instrument in the green room.
I used to also always have a spare pre-amp in my rack. Since I use stereo power amps in theory having two amp channels that would have to fail at the same plus a spare preamp would cover me in the event of an equipment failure. Virgo thing...
