UPDATE - October 8 - the issue has been traced to a bug in OS 10.13 / High Sierra.
The Music Importer, as the deprecated program was known, would scan your music library in its default location, then move music into Amazon’s “Cloud Player” service for streaming.
The app not only keeps your music up to date as you purchase additional songs from Amazon or i Tunes or as you rip CDs, but it also lets you access Prime Music, including that service’s over 1 million tracks, hundreds of playlists, Prime internet radio stations and more.
The app also supports Amazon’s “Auto Rip,” which is when you buy a physical CD from the retailer and it puts the digital copy in your online collection for free immediately after purchase.
Streaming has been eating away into digital and CD sales for years, as consumers turn to online services like Pandora, Spotify, Amazon Prime Music, i Heart Radio, and now Apple Music, among others, to listen to their favorite songs and artists.
Alongside this shift, it seems that users are becoming less interested in managing their collection of MP3s, in favor of getting the tracks they want delivered on demand, via streaming.
Pure Music DSD Bookmarks appear as such files (sample rate 2,822.4 k Hz and higher).