Ibanez S2120x vs. S2020x switching

[smokingvince]

hi, what's the difference in pickup / piezo switching options between
these 2 guitars

The S2020 has a small recessed black button in between one of
the (volume?) knobs & tremelo. Whereas the S2120 does not.

What does this button do exactly? Is there any advantage
to having the button in terms of greater versatility? Why
does the S2020 have one yet the S2120 doesn't?

Is there an illustrated diagram somewhere which explains
switch/knob functionality of S2020 & s2120? Which one
would you want if you had the choice?

thanks in advance,
-sv

[Gresh]

The black button is there to select between the output options for the 2020 and 2027 (RIP). The choices are 1) separating the output jacks...one for mag and one for piezo, or 2) one output covering both...but not in stereo and you can't blend them. I believe that part of the upgrade for the 2120 and 2127 (RIP) was to configure it so that you could run both outputs simultaneously.

I might have some of the details mixed up but that's the general gist of it. Kevan here would be the one to ask...he's the double edge guru around these parts.