Thought at age 60 I'd outgrown yielding to the subtle temptation of buying myself something that's clearly a desire and not really a necessity. My Epi SG400 and Fender Champion 20 are capable of producing such beautiful music.....so much more than I'm capable of extracting from them. But, I gave in and did it anyway.....a new Boss Katana Mk II, 100 watt single 12". I'm 3 years into this guitar thing and take to heart what you long-timers advise. I still remember Col Mustard writing "the tone chase is a death march".....sounded logical coming from an old pro. What I took from that subtle wisdom was that one should learn to play the thing instead of getting wrapped up in gear and chasing some ever elusive tone. You won't see me with a pedal board, but I've got an amp that'll probably last the rest of my days. Please educate me though.....I've seen several amps with this feature. Why does one need 2 volume knobs and how should they be used?