DVD-Audio is the pretty-much dead high-resolution audio (and video) format that competed with the also-unsuccessful SACD disc format from Sony. DVD-Audio players could play both stereo and 5.1 surround sound discs. They had video output (unlike SACD), as well as backwards compatibility with DVD-Video discs. SACD, though, often had a CD layer, allowing playback of the same disc in older CD players or in the car.
DVD-Audio's highest level of audio came via Meridian Lossless Packing which was a codec that could reproduce a convincing copy of the master tape mixed in stereo or 5.1 surround. DVD-A maxed out at 24-bit/192 kHz audio.
Record labels in their infinite wisdom forced consumers to use 5.1 analog outputs for MLP because of fears of piracy. They should have been fearful that consumers would reject the format because of a lack of quality titles, the $1000 cost of the players, the cost of the eight cables needed and the need for a new surround sound AV preamp. With only a handful or two of top titles ever released on DVD-Audio, consumers in the mainstream rejected the format and it is no longer supported by major labels.
MLP is a key component of Dolby TrueHD, though, which is found on many Blu-ray discs.
Eventually universal players arrived that could play DVD-A and SACD, though it was too late to save the format. Today companies like Denon and OPPO make Blu-ray players that can play SACD and DVD-Audio discs.
For example, check out a review of the Oppo BDP-83 Special Edition Universal Player.
For even more on DVD-Audio, check out the Wikipedia page.