D-321

The D-321 is a better-equipped early ESP model from 1993 that paired three-second buffering with optical digital output and stronger overall sound credentials than most players around it. Sony gave it a more substantial chassis and the kind of feature set that let it sit comfortably between everyday portable use and more serious home-system integration.

Anti-skip had already become important by then, but there is still room for players that needed to function like proper audio components too. The D-321 belongs to that overlap, where portability and line-level seriousness still had to coexist. That makes it one of the more revealing models of this transition period.