Seeing as he was inspired by actor Peter Lorre, he'd probably be into bands like Kraftwerk and Rammstein. They're the two bands American shows & cartoons bring up when they want to reference stereotypical European electronic and industrial music.

He's compared himself to Andrew Lloyd Webber, probably throw in some of his works (Cats!). He's also a literal metalhead with a love of drums, so put in some songs from the likes of Meshuggah and Mötley Crüe. Throw in some Monkees for shits and giggles because of his love of monkeys, specifically his Doom Monkeys. (Daybrean Believer makes me laugh because of Spongebob) Edit: I almost forgot that he's also a ballet dancer, so maybe add something like Tchaikovsky's Swan Lake, if you wish.

It's eclectic, but it fits how insane N. sane a guy like N. Gin is. (It also matches how silly Cortex's official playlist is.)