I struggled back in the 60's and early 70s with a 50 watt bassman. I tried a variety of cabinets, some with EV's, folded horn, etc. all quite efficient but it NEVER had enough power or headroom. Even at fairly low level practice in a small room. It was the worst bass amp I every used. I still have one, but it's for guitar only.
I did work on a few 50 watt Bassmans for customers that insisted on using them. I rewired them to use 6550's and quadrupled the B+ filtering. That made a big difference getting them to nearly gigging levels.