For the AC over DC, that makes me feel better about whether or not it would fry my arduino. The only thing though, I was unable to effectively do capacitive coupling for the guitar's signal. When I would apply the DC to it, it would just stop any sound. I was using a small cap (don't have any 1 farad non-polarized lying around) so that may be the issue, but if not, have I then done something wrong?
I would prefer to utilize a single mono cable (They are easy to come by, and if anything happens on stage I can easily swap it out; To make it backwards compatible without adding a proprietary jack beside the 1/4"; I don't want to use a Stereo 1/4" because I worry a roadie would put a mono in by accident and it would short my 9v to ground/I would have to add short circuit sensing circuitry to my pedalboard, which I find overkill if there is a better solution to just using a mono cable).
And I would go for the Due, only I would need 16 bit ADC and DAC at a minimum and would preferably use a 24 bit set, and space is an issue. I would need a Due the size of the Nano or Pro Mini to fit in the guitar. I could use it as my pedal board's processor though. I will look into that, thanks!
Current question: what would be the correct value cap to use for a 9v powered system(I may use diodes to half/full rectify the signal to stay at about 10v then regulate it before the arduino, or figure something out), that also has a min resistance of 8k ohms, max of 25k ohms?