I am mainly interested in classical music: To get the best possible sound quality from my HiFi gear and to be able build up a user friendly system for the meta data. A suficient meta data system should after my opion be able to give an overview of different versions of a certain composers compositions. E.g. when I search after Mahlers 4th symphony in my collection, I should get up all versions 1) by conductor 2) by orchestra and solists 3) by production year. The meta data shhould of course also contain other information accessible from the CD or download.