Drum N Bass in CommonLisp [video]

Fun starts at 45s: https://www.youtube.com/watch?v=jS84KmkkNkU&t=45s

Working with Impromptu or Extempore looks similar. What is the advantage of CL supposed to be in this use case? Apparently it uses the Lisp version of Common Music, which switched to the Scheme S7 interpreter many years ago.