Huge +1 on Blues channel love! The gain knob set low gets you sweet semi-cleans that are rich with chime and tight bottom, and set past 12:00 gets you more saturated-but-smooth tone that is rich and defined, never the "smeared tone glob" which is what happens often with increased gain settings. It is a superb channel, and my personal favorite voice of the Express, even for cleans ...which I use for my
clean and
semi-clean tones, oddly enough. For more saturation, I go for the Crunch channel which to me is analagous to the Blues channel "ending" and the Crunch picking it up to go further. FWIW, for my style, I have no need and no love for the Burn channel ...just too heavy and "tight" (some dig scooped, but that's just not my bag).
As for specific settings, I find that the gain knob set sub-12:00 is perfect for light breakup for single coils, and even close to 9:00 for buckers. Of course much depends on your pup's wind, but you get the idea. Going past 12:00 really gets harmonically rich and swirly, thickening tone and attenuating highs for more mids ...very chewy and (yeah, you guess it) "bluesy."
I can't really make meaningful comments on tone stack settings because I changed tubes (went for lower-gain NOS-ers) which not only gave me less overall OD in the amp (which is fine since this and every Boog I've ever owned always has OD to spare), but a more
usable range of OD. That, and made the notes more defined, more individual distinction. It also allowed me to bring the treb and bass knobs higher that I ever could with the stock Mesa tubes, so I get a more usable range (IMHO) in the knobs, to boot. So in other words, my tone knob settings are way out of whack if you're loaded with the stock tubes. But start with less: less treb, less bass, around the 9:00 area to get your general tone. The mids are more tricky since this has lots to do with your pups' voice. For example, I raise the mids for my Strat and Tele, but decrease the mids with my Lesters. One of the great things about Boogies is that the mid control does lots to "nuance" the voice, as if you're bringing your guitar more forward or backward in the mix.
Oh, and this is my 5:25 with 10" combo, so if you're a 6L6 or 12" user, YMMV. Sorry to get verbose ...but I hope this helps someone a bit
Edward