In my experience, you don't have to have a DVD-A player for all the DVD-A disks out there - but it helps.
Obviously to get all the benefits (extra high quality, and multichannel) of DVD-A you need a DVD-A player, but a lot of the DVD-A disks have a Dolby Digital 5.1 version on one of the layers some were that will play in a DVD player
Bjork's Vespertine is dual sided. On one side are two DVD-A versions (2 or 5.1 channel?), flip the disk over and you find stereo PCM and DD5.1 versions.
err! I have ONE disk, but I
hope most DVD-A are like Bjork's