Treble boosters, old-school fuzzes and overdrives (anything pre-1970, really) go into the front input because they're not friendly with buffers. That Input, despite often being in the red when those sorts of pedals are engaged (especially Range Masters), has zero problems and I don't think I've ever heard it clip. Just about everything else is inserted through i/o 3 so I can place it anywhere in the signal path, in mono or stereo. Boss pedals, Klons, delays, chorus pedals - everything with a buffer and some with true bypass can go to i/o 3. I've made nearly 3000 pedal/gear demos and at least 1000 of them have been made with the Axe as the main platform. When I first started using it that way around 7-8 years ago, I got the expected "I wish you'd use a real amp again, man.." comments. But I persisted because the Axe is my 'real amp'. It's all I've used pretty much in here and on stage since 2013 or thereabouts. So I've forced a sort of sonic conformity on my viewers. I don't have as many subs as the younger channels but they're not going away; they're still slowly increasing. So I'm not looking back. Sorry for the long-winded answer!