Win 10 HTPC, Netflix App - will give you Atmos perfectly.
There is barely any Atmos content on Prime.
HTPC with windows 10 - no siree!
Won't touch it with a barge pole
Here is one of the 100 different things wrong with Win 10 today :
YOu are in the middle of an immersive movie - out comes a popup- your system is going to restart in 60 seconds to install an update you neither asked for , nor care for
On a side note, I did try configuring a win 10 laptop hooked to the AVR to play Netflix after your post
Pass 1 - Netflix said something went wrong with a cryptic error code, googling the error code gave me an indication that the app was not happy with an extended display - changed to display 2 (AVR) only
Pass 2 - Netflix now worked as expected but with 5.1 audio only, checked the output device settings and it did show ATMOS capabilities but wasn't working
FUrther googling revealed that one needs to install the dolby access app in orer to get atmos so i did that
Pass 3: ATMOS now showed up as configured on output devices. Testing all the speakers through the output test screen on windows worked as expected... Great. let's launch netflix and voila, NF started showing the atmos logo as well on atmos enabled titles. Playback however still remained at 5.1
Pass 4: More googling showed I need to go into advanced output settings to enable apps to give exclusive control to the said audio device - did that too but no luck with atmos still-
Pass 5 - Found a reddit post that said atmos needs to be selected in the spatial sound settings subsection of the output devices advanced tab - did that but no luck still.
I actually have an old unused Intel NUC 5ppyh which should be able to run as a 1080p htpc comfortably at no added cost- but win 10 is an abomination
Now I am sure I can make it work with time & patience but a HT media player needs to be an invisible, simple device that works without tinkering.