Every studio player I knew had a version of this GK amp.
GK MB-112 Mine is 35 years old and was a variant of the MB-150. It's been all over the world with me. In the studio, just it and me. Live, plugged into any of a number of EVM-15L loaded extension cabinets.
Last time I was in Stockton, I dropped it off for a new speaker and to be checked out while I had lunch with my daughter at UOP. By the time lunch was done, so was my amp.
I still have and use it along with a single speaker extension that is never used anymore.