I hope this is an okay forum to post this in, but this problem is so obscure, I'm not sure where else to post it. I'm running into a weird problem with Mega Man 1 and 2 for NES. In both games, certain music tracks have a lot of audio crackling/popping in them. At first I thought it was something wrong with my setup, speakers, maybe the console itself; they haven't always been like this. But I went over to a buddy's house, and HIS copies both do the same thing! He has a straight composite into CRT setup, nothing fancy. It's only happening on Mega Man games and we noticed it a little bit on Bubble Bobble as well. 

What could this possibly be? AC adapter going bad giving dirty power? Something with the cartridge itself? Coupling capacitor, or even mask ROMs going bad?

From 10 minutes of Googling, it sounds like certain ROMS for classic MM games have buggy audio. The interwebs are also telling me that the buggy audio will still be present if you dump the ROM from the cartridge and emulate with an accurate emulator.

Hmm okay. My Googling only turned up Mega Man X threads, issues with the Retron 5, etc. I must not be doing the correct search.
I noticed one thread about the Mega Man Legacy collection for PS4 having this problem, as if Capcom used bad ROMs.