I was a long time Tidal subscriber who consequently added Qobuz and have also been listening to the free trial of Amazon Music HD.
The Amazon Music HD desktop app is crippled because it uses shared mode in Windows. It can not take advantage of Wasapi exclusive mode as Tidal and Qobuz can. At least on Windows it is not bit perfect. Whatever the native sample rate and bit depth is streamed it will be up or down resampled in Windows mixer to the user setting.
I am hearing degradation of sound quality in Amazon Music HD compared to Qobuz and Tidal which I attribute to shared mode. Amazon has their own forum and trial users have been complaining about why the service was rolled out half baked without
exclusive mode and no one is giving answers.
Considering the sound quality it does not make sense to save a little money over Qobuz. Despite the buzzwords they throw around I don't think Amazon is really targeting audiophiles.