I'm really interested in trying one of those GK MB Fusions. But I don't think I've ever played through a tube amp.
Interesting discussion.
Plus the GP comment about the Subway.
Here's my 2c.
I have played through 60s/ 70s Bassmans (or is that Bassmen?) for decades, basically until I got too old to drag them around. I LOVE how they sound.
I never bonded with the big tube Ampegs- I looked into them a few times over the years, but I just didn't like the sound as much as the Bassman. Just personal preference.
About five/ six years ago (when I was about 55) I decided the then current Bassman had to go and I wanted something lighter and louder. The Bassmans were never really loud enough by themselves although I had an out for the PA in the last 100 watter I had.
After trying lots of what was around (Ampeg, Genz, Mesa, TC, Aguilar)- I settled on the Fusion 550 with Neo 410 because I could make it sound like a Bassman being pushed and much more through better speakers. I am not good at describing sound but the GK sounded right to me.
I have since added a MB Fusion 500 and two Neo 212s. I honestly never get amp/ cab GAS any more.
I used a big Mesa rig (610 and some A/B head, I think) a lot in a practice space we used use and I prefer the GK sound.
I think the MB Fusion 500 (haven't played the 800) is a really good amp and it can get you some really nice tube tones but also allow you to get some GK grind.
It is a very giggable amp in my opinion. I often take it instead of the Fusion 550 because it is lighter.
I've mentioned before that the Fusion 550 is more like a thoroughbred.