Hey Wayne, Let me start off by saying that I use a Boss GT-6 and so does my fellow Guitarist. We both went through a lot of amps until we each found what we were looking for. We tried all kinks of tube and solid state amps, Fender Hot Rod Deluxe (tube), Vox AS100 watt Modeling (tube and solid state) THD class A 15 watt head and 212 cab (pricey sucker), Roland Cubes and a Roland Key Board amp. We also tried going just through the PA system. Now some of these didn't do to bad, like the Fender, it had a nice clean channel but not enough punch and low end, and the Roland Key Board amp nice and clean but a bit cold.
After lots of research It was pretty clear a tube amp was the way to go. But it had to have a great clean channel and good distortion too. I chose the Carvin V3 100 watt Head and a Carvin 412 Legacy cab loaded with Vintage 30s. This set up works great for me. This amp has a ton of features, one of my favorite being the two effects loops (yes two). I run my GT-6 and a Bad Horsey Wah through the first which is in Series and the second which is in Parallel I run a BBE Sonic Maximizer Stomp. The Parallel loop has a pot which lets me dial in just the right amount of the BBE. I absolutely love this set up. I have also found that using the amps distortion channels and the GT-6's effects works real nice. I always keep the expression pedal on the Volume setting so I can have control of the overall sound level, this lets me blend with the band in all situations.
My fellow Guitarist chose the Peavey JSX 212 combo it also has high end sounds and features. He also runs the GT-6 through his effects loop. We both agree that the versatility of the Carvin V3 sets it slightly ahead. But both amps have wonderful overdrive and distortion settings with all the gain you could ever need, and the clean channel lets you use the GT-6 settings/patches without sounding muddy.
My advice is to buy a high end tub amp with a great clean channel so you can get every bit out of your GT-8.
Hope this helps, Bill Kelley