Hello, i write from Sardinia, and sorry for my "strange english.."
i have MkII head (100..) firmware updated and i have a strange, annoying and blocker problem from 1 mounth:
i start to play for 20/30 minutes with high gain sound, and as if by magic the sound crashed, rather and my MKII transform the sound, clean, crunchy, no sound and than return original after the sound starts to decrease.
exemple: i play a power chord, strong with high gain (mesa suond), so start the magic... clean, cruncy, clean, only mosquito bass, crunch and in the end of power chord sustain, return normal mesa sound.????
So I remove the cable and connect behind the head to the pre out, here the sound is perfect, clean and valves work perfectly. after this, attack at the main entrance and the mkII works good. I also changed cabinet and cables and home (maybe i think is the electric energy..) to the test, from 2X12 (my Randall 212cb) to a Peavy 4X12. Same problem.
Thanks a lot!!!!!