The instrumental song that plays during the scene where Frasier (Kelsey Grammer) is trying out different styles of furniture in his apartment is a pop song called "Classical Gas" by Mason Williams. While the song was a minor hit in 1968, and very popular with educators who hoped its influence would guide young people to real classical music, it's not anything that Frasier himself would deign to play in his home. In fact this is the only time Frasier will have guitar music of any kind on his stereo.
The title is a nod to the famous 1903 American film short, "The Great Train Robbery."
Dudelsackpfeifer is German for bagpiper.
Ironically, the last apartment styling that Fraser attempts is a knock-off of the style his arch-enemy Cam Winston will adopt the following season.