Would this require a re-set? Yamaha APX600 factory strings to Martin MA550's (from 12-16-24-32-42-53 to 13-17-26-35-45-56).
The main things you will want to check are:
- Do the slots in the nut allow the heavier string gauge? If not, you may have tuning stability problems or problems with the strings sitting at the correct height above the fretboard.
- The bridge must accept the thicker gauge strings. The bridge pin and slot for the string need to be able to hold the string firmly but you shouldn't have to use excessive force to insert the bridge pin.
- Heavier gauge strings will add increased tension on the neck when tuned to the same pitch as lighter gauge strings. With the neck pulled slightly more, it will tend to cause a bit of "forward bow" (or "up-bow" or "relief") in the neck. This raises the height of the strings (action) a bit. The adjustment for this is the truss rod. As a beginner, I would recommend you have a luthier make this adjustment.
I don't know much about the APX600, but I don't think 13-56 strings should be a problem. That said, I think lighter gauge strings are easier to learn on, so you might be best served sticking to 12-53's for now.