In Emulators / NES ROMs

is there an easy way to convert mp3s to nes music ? Help would be appreciated.

Simple answer: No.

Complex answer: Most MP3's require more storage space than the NES has access to, even with it's most complicated mappers. The decompression and playback of MP3's requires very fast, or very dedicated hardware, which the NES does not have.

While the NES CAN, in theory, play back digital audio, playing back MP3's or similar highly compressed audio formats is not even remotely viable.

Midi is a closer match to the NES's capabilities, but even then the midi specification exceeds the capabilities of the NES to the point that most midi files would probably need extensive editing.