I look at it like the transmission of a big truck.damn! even i kinda want that
I wonder, if you bypass all three does it buffer your signal three times?
I could see something like that working - but not for stacking, for three different presets.
I'd build it with four footswitches: one for bypass, and three to select which is on at-a-time.
Like on the programmable loop switchers where the last footswitch pushed takes priority.
If ever a boss pedal needed presets, it's the Metal Zone. There are a few usable sounds in the thing, but there is an awful lot of terrible too. The knobs are VERY sensitive to position changes so ever finding a good tone a second time is very difficult.
This reminds me a bit of Craig Anderton's Quadrafuzz. Only it splits the guitar signal into four EQ bands, then lets you set the distortion level independently on each.
https://www.paia.com/proddetail.php?prod=6720K
I have a modern multiband distortion, the Source Audio Pro Multiwave that distorts 10 bands separately. A bit odd since it's digital (although certain modes sound like nice analog OD) but it definitely has some great tones in it, as well as some that are just plain sick in a usable way.
The coolest thing is that it has six presets arranged in two banks of three - and with an expression pedal you can morph seamlessly between any program and its counterpart in the other bank. Pretty wild results morphing between two presets that use completely different algorithms; some truly crazy sounds to be had in the middle ground.
The pedal includes the Source Audio programmable 7-band EQ, also with morphing. I have one pair of presets set up as clean EQ only, so I can sweep between two EQ settings.
Pete Thorn made a demo using this unit about a decade ago.
https://www.youtube.com/watch?v=GKsQZPzSLI0
Coupla years ago Source Audio came out with a newer version called the Ultrawave.
Back in the day there was also a stripped-down original Multiwave, just the core engine with no presets or EQ,
https://www.youtube.com/watch?v=vePtiyyBo4s
Pete Thorn made a demo using this unit about a decade ago.
https://www.youtube.com/watch?v=GKsQZPzSLI0
Coupla years ago Source Audio came out with a newer version called the Ultrawave.
Back in the day there was also a stripped-down original Multiwave, just the core engine with no presets or EQ,
https://www.youtube.com/watch?v=vePtiyyBo4s
Why stop with 3?