I have the MG 800 and it’s a fantastic amp. I tend to use the contour on the blue channel but mostly off.
I found the orange contour played loud started to sound a little harsh.
They are great amps and I run my Darkglass Omicron pedal into it and it sounds glorious for rock.
One of the most underrated amps you can buy in my opinion and I’ve had most out there to compare to !!