Hi there! I'm trying to find a gift for my resident bassist. He's got a 15W 10" bass amp which for bass is only enough for rehearsals. He started gigging and I want to gift him a new amp. Something that can be connected to a concert setup as the band is about get their hands on loaned equipment.

I know in pro set-ups there's an amp head connected to some speakers. And somehow that is connected to overall concert sound system. How is that connected? Is that "output direct connect" I see in some combo amps?

Where can I read about it? All I've found online was useless. I guess my lack of basic knowledge prevents me from asking Google the right questions.