A common refrain amongst music listeners today is that so few viable new genres have sprouted up in the past decade; yet they all too easily discount musicians whose output is a(n)______ of other styles, as though no previous genre ever borrowed from several preexisting genres.

The sentence begins by stating how music listeners complain that so few viable new genres have sprouted up in the past decade. And then the next sentence begins with a "yet" to indicate a behavior or attitude that is in contrast to how such listeners ought to behave. And the blank is embedded in this part of the paragraph.

yet they all too easily discount musicians whose output is a(n)______ of other styles, as though no previous genre ever borrowed from several preexisting genres.

The sentence says these listeners easily discount (diminish) the musicians whose output has some type of relation with the other styles. And it chastise these listeners by stating that "as though no previous genre ever borrowed from several preexisting genres" , implying that the listeners seem to think no previous genres have ever borrowed from their previous genres. Hence, clearly, the criticism or the discounting of the musicians by these listeners must be because the musicians' output has borrowings from previous genres.

Hence our word for the blank should be "whose output is a(n) a mixture of borrowings (from) of other styles.

The word from the list of choices is amalgam.