Help me find headphones for an electric guitar + backing track (under €100)

Hey, I need some advice. My boyfriend plays electric guitar every now and then in the afternoon. He uses an amp and a Bluetooth speaker for the backing track of the songs he's playing. Since the neighbor is constantly complaining about the volume, I was thinking of getting him some headphones for Christmas to plug into the amp. But I’d also like to figure out if there’s a way to connect the backing track to it as well. Any suggestions? Bonus pooint if you can recommendsome good models. Around a hundred (euros) is fine, but less is even better.

Sorry, I’m a bit clueless about this stuff!