That combination would jar (guitar belongs to the Irish Jig composition, and the other three belong to the jazzy waltzy composition.) This would cause Rinoa to complain about the music and cut the night short, which would move things along, but isn't as dramatic.

The waltzy/ jazz composition (Electric guitar, piano, bass guitar and sax) (SPOILER)has the night end with a bit of an argument after Rinoa thinks the music sounds wrong, and Squall doesn't seem bothered about what she's talking about

The irish jig (Tap, violin, flute, guitar) is more dancey and lively, (SPOILER)and the night ends in a bit of a nicer way. Rinoa seems to prefer the music, and she succeeds, partly, in getting through to Squall