First off HDTracks does nothing (unless it's there label, Chesky). They get the 24 bit files from the labels they work with. For their own Chesky label they record in 24 bit digital so these are easy 24 bit transfers. For some labels (like Warner) they have folks like Bruce Brown (Puget Sound) take the 24 bit DVD-Audio tracks and transfer them to files ready for download. For recordings that were originally DSD files, Bruce does the DSD-to-PCM transfer (which usually ends up at 88k or 176k).