Although this is a listening challenge, let's start by looking for pieces we can listen to *and* access in print. UWM's music collection includes scores and parts for chamber music groups up to 13 players; scores and music books are located in the east wing of the second floor of the Golda Meir Library.
Finding music for a specific number of players AND a specific date range is tricky, unless you understand how scores are organized in library's like ours, that uses the Library of Congress classification system. The Library of Congress system groups materials together by subject area; for scores, that means by instrument or ensemble. The "call numbers" assigned to each score also include a publication date.
To limit your search results to just scores, and to limit to works from 1980 or later, you can use filters or limiters found in Search@UW. You might be familiar with filters from online shopping and other websites, where you can narrow your options using different criteria. Here's a quick intro to using them to find scores in the library. You can use the same approach to limit your results to Audio/Visual resources (including physical recordings and streaming tracks) by choosing that filter.