TS, as the emphasized part of the material Jack quoted pointed out, DVD-As also have a DD and/or DTS track which can be played on any DVD player, not just those which can play the DVD-A track. What's doubtful is if "lower quality" is an accurate assessment in the real world. Although DVD-A/SACD offers theoretical resolution advantages because of higher sampling rates and/or bits, as the engineer/movie music editor "soundhound" I've previously linked to here explains, the significant differences are multi-channel(where present)and better recording, mixing and mastering, not sampling rates or bits.
