Hello atp327,
Welcome to the Apple Support Communities. From your post, it appears that songs are stopping in the middle of the song or the song quality is worse than expected. We'll do what we can to help.
If these are songs that were imported, try reimporting them again: Import music from a computer to Music on Mac
If these are from the store and are downloaded, try deleted them and redownloading them again: Redownload apps, music, movies, TV shows, and books
Otherwise, this general troubleshooting might help since Music is a system app:
Thanks, and enjoy your day!