One of the leading portable digital-audio player makers is closing shop at the end of September, meaning the industry will lose a company that helped start the market. In 1998, Diamond Multimedia, a company well known for video cards, released one of the first portable MP3 players under the Rio brand. It took Apple Computer's introduction of the iPod in October 2001 to popularize such devices, but Rio was there at the beginning. The company's current flagship products include the excellent Rio Carbon and Rio Karma devices. Although Diamond released some great devices, the company was never quite able to compete with Apple, which holds a commanding market share of almost 75 percent in the digital music player market in the United States. The Rio went through many ownership changes; S3 bought Diamond, which later spun the company off as SonicBlue along with ReplayTV, and later sold the Rio assets and brand to D&M Holdings, the company behind high-end audio products Marantz and Denon. D&M Holdings has announced plans to shut down the company because it believes the high investment necessary to stay competitive in the digital-music player market is no longer worthwhile. Goodbye, Rio. We'll miss you.