HDTracks does not master any of the stuff they offer (except the titles from Chesky Records, which they also own.) As a store, they put up for sale whatever the labels provide them. There is almost never any real information on the provenance of the recordings, and how they were mastered. The one thing they do is guard against upsampled files...if the stuff was recorded at 48K for instance, then 48K is the highest sample rate they'll offer. If it's from an analog master and they offer it at 192, that means it was transferred at 192 and not upsampled from the CD. If something you get from HDTracks is slammed, it's because the label provided a file that's slammed. And we're all aware by now of the various ways that decision can come about.
There are a couple of other online stores for hi-res files:
http://prostudiomasters.com, run by a guy who used to manage the tech side of HDTracks.
http://store.acousticsounds.com/superhirez, which offers DSD as well as PCM files, is a part of Chad Kassems's empire.
http://bluecoastrecords.com, Cookie Marenco's company which also offers both DSD and PCM
And a couple of labels offering their own catalogs. And of course, someday, Pono.
