First, he transposed At the Gala into D flat major. If you are a musically-inclined pony fan, you probably know that changing the key of a piece can give it a different sound. As Dimondium said when he sent this to us, At the Gala in Db major sounds awesome. You can find this version on Youtube, or listen to the midi version.
Second, Dimondium wrote an original piece called Spitfire's Theme. It's a very chill piece of music, because Spitfire is so cool. Listen to Spitfire's Theme in the embedded video after the jump, or visit Dimondium's Youtube channel.