Most recent DVD-A's have an independent stereo track which is generally (always?) found in a separate "Group" in DVD-A-ese. Switching "Groups" can require hook-up to a TV screen. My Panasonic lets me do it without a television; my Pioneer requires the TV to navigate. As a pure audiophile, I find it annoying to have to turn on a TV to listen to music.
For discs that do not have a dedicated stereo track the player will do its own mixdown into two channels.
I consider SACDs and DVD-As to be of similar quality. Any difference is dwarfed by differences in the recording/engineering/mastering from one disc to the next.
My SACD collection is much greater than my DVD-A collection, as I listen primarily to classical and jazz.
In jazz, I would try to track down Mingus Ah-Um. There's some great Bill Evans with Scot LeFaro, Chet Baker - Chet. And "Time Out." Lots of Miles, although by this point there have been so many reissues of "Kind of Blue" and some of the other classics I don't think you can ever get any consensus on which sounds best.
Classical is the mother lode. Try some of the Red Seal releases They're almost all good - and budget priced. The new favorite is the Morton Gould/Aaron Copland disk, but don't miss the Reiner /Bartok Concerto for Orchesta and Scheherezade (sp?).
And speaking of new favories, the Alison Krauss disks are spectacular, especially the live one.
