the ipod offers better convenience, not technology. dvd audio is superior but most people won’t appreciate the quality if they have no problem with ipods.
DVD Audio also has DRM on it. One of the reason why it (and Super Audio CD) never took off was because of DRM. Personally, I think that the RIAA only hurt themselves more when they started installing DRM on regular CD’s. Each DRM method they tried was cracked right after release, and their efforts ended in disaster two years ago, when Sony sold DRM-laden CD’s that installed spyware on people’s computers. Since then, the major labels have abandoned putting DRM on CD’s.