The most memorable stacking success that I recall was from roughly a couple of years ago. I was running a Bosstone-like fuzz into a mildly modified OD-3. It was a more rare instance of having three equally great sounds. The OD-3 on its own was fairly mild, kind of like an amp just starting to budge a little bit, just starting to sweat some. The Bosstone on its own was "pretty much Spirit in the Sky," if that makes sense. The Bosstone into the OD-3 had this incredible vibe with controllable feedback at somewhat modest volumes. The OD-3 tamed the Bosstone's buzzier characteristics just the right amount - it made it so that there was almost the effect of running a fuzz into a dimed amp.