I have my amp set to a pushed/crunch type of thing. With that said I also always have a EP booster always on, and my klone is practically always on. I will also stack 2 fuzzes into seperately, and or a BB pre or eternity in all of this. So if you're keeping count, that's 6 OD/fuzz circuits into a slightly distorted amp. My secret is all of them are housed in 3 dual pedals so it keeps the board quite small
I'm all about two channel amps. I honestly think it just sounds better, I got tired of my fuzzes flubbing out. No OD pedals on my main board. Takes away from my reverbs and delays but when I am playing my loud clean amps or my "Marshall" rig, the BAT Witchburner is all I'll ever need. I've never gotten into using multiple dirt pedals but I've always chalked that up to my laziness and unoriginality. If I need less gain or some ****, I'll just use my vol/tone knobs.
I run my amp hot enough to clip, but then attenuate with an always-on compressor and add a little grit and warmth back in with my Timmy. There are other ways to do what I'm doing, but for me it's the best way to get the feel of playing my amp louder but at a lower volume. I also have 2 fuzzes, 2 other drives, and a clean boost on my board. One fuzz has a clean blend, so it's set for a clean lead + dirty rhythm sound.
I run whatever amp I'm using cleanish with a bit o hair. Any drives I use I have setup as different flavored boosts to kick the front end. They all have a different personality. The order depends on stackability...
Unity gain. Look that term up to understand how to control your input.
As far as output, send your output to a mixer and find out where your device's 0db input gives you 0db output.
I know anytime I switch things in and out my level is consistent. Even times a "venue's stage" makes my levels seem out of whack, I'll tell the sound guy during sound check..."I got this...I got this...etc..." I'll run through the gamut and he'll tell me the levels are solid.
Also, once you go through the process of leveling, mark everything...and live by it. It's a hassle getting there but if you can put in the same spot everytime, you're golden.