A 100 – 150 watt bass amp is the bare minimum to use for rehearsals and small gigs; 300 watts is better since it allows the amp to push out the same or louder volume with less effort or strain. A louder amp doesn't have to work as hard, which means less chance of overheating, blowing a fuse or damaging a speaker.Unless there's a house PA that can handle the bass, you're likely gonna need to buy or borrow something bigger. I'd
love language test say 250W is minimum. Depends on the act's style of course, a 100w would possibly work with a drummerless acoustic act...I typically recommend between 300 and 800 if you are playing larger auditoriums without a sound system to play through or are playing outside. Anything larger than 800 watts is overkill because any venue where you would need that much wattage will have you playing through a sound system.