I use a Fulltone Fat Boost. It's hard to believe anything can enhance the sound of this amp, but this thing enhances the sound of ANY amp. The LSS is unfriggin'-real sounding with a Fat Boost.
I also use a vintage TS-9 for some smooth saturation. But if I am going for a classic rock overdrive sound (Jeff Beck, Joe Walsh, Led Zepp etc) I have a Rob Keeley Rat pedal that just ooooozes classic distortion tone through this amp w/ the pedal level (volume) around 1:00 and the distortion only at 10:00....it is pretty sweet. Also the Keeley Rat has 2 extra modes toggled in w/ a 3-way mini toggle that make for nice pallot of other tones. In one mode, you get the classic RAT, in another it is like a mellowed out classic RAT sound with a bit of a boost in the bass; the other mode is a clean boost, but I much prefer the Fat Boost for that.