You’ll need some M1 Decrypted files to have sound in games! Check the MAME Compatibility Spreadsheets! I’ve helped the PiFBA list, testing more than 100 games and writing what the games need to run fine!
Raspberry Pi B+ - Mini Bartop Arcade - Retropie 2.6!
Raspberry Pi 2 + PS3 Controller Wireless - Retropie 2.6!