Silly question about Operating Voltage

Good day everyone!

I’m developing an audio project which uses analog signals from 100-1400 Hz and voltages from 0-5 V. I’ve been working with the UNO board, but since experimentally it seems to no record correctly the data, i’ve been considering changing to this board. My question is about the Circuit Operating Voltage, which in the UNO board is 5 but in MKRZero is 3.3V. The Datasheet of the board says that by simply connecting an external regulated power source to Vin, you can supply the board up to the source voltage, thus, I want to know how does it apply to the ADC readings and which cautions do I have to take to not damage the board. Sorry if this has been questioned and asked before, but in case of buying a MKR Zero I wouldn’t want to buy a second unit.

You should not subject any of the IO pins of the MKR Zero to more than 3.3 V, otherwise you will damage it. You can power the MKR Zero with 5 V on the Vin pin only because there is a voltage regulator on that pin that drops the 5 V to the safe 3.3 V.