Hello Keberoxu,
Where did you encounter the lyrics quoted in your post ??
Looking at lyrics sites, I find the following:
Flanders: With the tone control at a single touch,
Swann:    Bel canto sounds like double Dutch.
Both:      But I never did care for music much,
          It's the high fidelity!

My own recollection of the line was ...sounds like Donald Duck.
Haven't any idea what "double dutch" sounds like, or perhaps
the phrase means something different in UK than US (double dutch
was a jump rope game)…..
   https://www.youtube.com/watch?v=wI46rsQR83k


Thomas.