I just found a lot of the Sheffield lab collection on Amazon HD. Fantastic stuff. Very well done and high dynamic range. (even if it's 16/44)

Just type in Sheffield labs in the search section. Have fun!
Bstatmeister said above: "...even if it is 16/44."

Nothing at all wrong with CD quality 16bit/44.1khz.  That bit and sampling rate was designed to fully cover the frequency and dynamic range of human hearing.  Human hearing does not advance with technology...it is a constant.  It is unlikely that even a TRUE, ORIGINAL 24bit recording could be distinguished by the average human.  A well done 16/44.1 recording is all anyone needs.  Anything else is an effort to deceive you out of your money.
I first got an upsampling DAC about 10 years ago, PS Audio Digital Link III.  While I intellectually understand that upsampling shouldn’t sound better, about 90% of the time it did.  I listen primarily to Classical Music, and upsampling would increase the believability of the Sonic picture.  The soloist, percussion, strings , brass and winds seemed to occupy their own little zones, as they do in a real concert, .  My present DAC, the Bryston DAC3, has an upsampling feature and I don’t use it much, but the results are impressive when I do.  I have to say that the algorithms that determine what should be added to a 16 bit recording do a damn fine job.  Maybe it’s different
for other genres, but I don’t listen enough to comment.
  I will now sit back and watch as others tell me that I shouldn’t be enjoying what I enjoy, and that I have no street cred as an audiophile.
btw..was Amazon Music Server down today?  I don’t have the new service but I did buy many Amazon mp3 downloads years ago and usually stream them to the bt receiver in my car, and I kept getting a lack of service notice today