How's it going fam.

Modded a few Super Gameboy 2s for personal use and the RCA prosound is a bit noisy compared to other SGBs I've modded in the past. Was wondering about your thoughts on if it might be the capacitors going out. I don't have a capacitor tester to check them at the moment.

They are SMD components and was thinking of replacing them with through hole components.

I've never heard of that, but replacing them couldn't hurt. Be aware that if you test them, you'll probably want to remove them first. So you may as well just replace them without even testing them, because it's cheap and why not?