Henry I. answered 04/24/19
Experienced, Patient Math and English teacher
It is true that in ordinary English conversation, we would likely place the prepositional phrase (with the music...) after the verb (was mixed). That does not, however, establish that there's an error in your text. An inversion in word order, which you were sharp-eyed to catch, can be a function of an older style or simply the author's effort to place an important phrase earlier in the sentence or to juxtapose phrases that are best placed together.
Thanks for a good question!