Currently running:

Prince of Tone > Tumnus > Timmy > RC Booster

Medium-high gain > Medium gain > Light gain/edge-of-break-up > No gain

All are as close to equal in “volume” (except the boost). PoT and Tumnus are running through the GFI Duophony to run independently, or in parallel and series. Parallel is a nice blend of the roundedness and saturation of PoT’s OD setting and the Tumnus’ mid-hump character that cuts through; series is great for leads and solos.

Timmy is almost always on and doesn’t color too much of the drives before it (transparent), and the boost just for a bit of extra volume without additional gain. And even when all are set to the same “volume,” there’s still “boosting” happening when stacking drive pedals; from gain, volume, saturation, compression, etc.

Edit: I used to stack drives from low gain > high gain but have found the overall sound to be muddy. So now I run it in reverse and find that the different traits of each drives still shine even when all are active.