My current rig includes a GK Backline 600 amp. I know it's a budget model but it does the job and I've never had a compelling need to replace it. In our practice space I use an old GK 400B that is borrowed from a friend of my bandmate. It's been deemed too old, noisy and unreliable to be gig-worthy. I can't even read the writing on half of the controls on it because it's worn off. I really like the sound of the 400B. Somewhat tubey sounding to me, although I'm pretty sure it's a solid state amp. I'm thinking of upgrading my amp in the next few months. What I'm wondering is whether I would get more of that character sound if I were to upgrade from my BL 600 to an MB500 or MB Fusion. I'd like to get a micro amp, but there are so many choices - I'm inclined to stick with GK.