I have Amazon HD for about 2 years now. Very happy with it. I just had to try Qobus though. I have a pretty good system, about 20k. What I noticed is Qobus does sound BETTER, tighter, more dynamic, just more clarity and oomph.
Amazon is much easier to navigate and use, their format is better, IMO.
Qobus has been a nightmare at times to use, not really user friendly.
I have noticed with either outboard DAC i own, that Amazon will generally register a song as HD but, doesn't always register exactly what the streaming rate is properly. With Qobus , my DAC's register exactly what the streaming rate is. Be that 16/44 24/192 24/96, etc. Amazons streaming wont do that, I don't know why. Some how I think Amazon is cheating somehow or somewhere? I am still keeping both for the time being. But, every time I listen, it is always Qobus I prefer. Just sounds better. I will say that Amazon sounds very good and is easier to navigate though! Robert TN Hope this helps someone.