Amazon HD Lower Price

don't mix Amazon in with the other 2 you wrote about 

Well, I have Amazon HD and I'm able to stream 24bit/192kHz through Fire Cube to NAD M17V2. I can also stream Amazon HD through the BluOS, but I prefer the Fire Cube / Amazon Platform using the FireTv remote instead of an app, using the phone or computer. Also Amazon Music include lyrics on most songs. Both streamers will do 24bit/192kHz. Bluesound has a little more laid back sound, maybe a little bit cleaner, less noise, but not a big difference. I had Tidal Music service along with Amazon Music and I still preferred Amazon. I'm very happy with Amazon Ultra HD.

Dyson 2004

"When Apple roll out their HD service in June, how do I stream their music through my external DAC? Their Apple TV box doesn’t have any digital outs except HDMI. I can’t think of a way to do it."

You need to hard wire a streamer to your DAC. I use a lap top to run the Music app then USB to the DAC. Wireless Bluetooth does NOT support HD music streaming.

Same here.  Free upgrade to Amazon Music HD.  Must go to your account and accept changes.