Voom HD Networks was a suite of fifteen high-definition TV channels. Launched in 2003, it offered a significant increase in the number of HD channels available in the United States at a time when only a handful of basic cable channels could be seen in HD. Problem was, the networks didn't have much high-profile content, and once the established cable channels launched HD simulcasts, distributors dropped the Voom networks, and all channels were shut down in early 2009.
The networks did however live on in Canada, as part of a suite of four channels that licensed programming and brands from Voom. One of those channels, the art and music channel Treasure HD, was renamed Hifi in August. With a schedule filled with documentaries, classic rock, jazz, and classical concerts, Hifi targets an older baby boomer demographic.
Thanks to Randall C for the tip!