Ok guys, it took me a few hours but i think i got to the bottom of it. I will post my findings in the unlikely case someone finds them useful in the future:
Using the fire stick as a music streamer:
- as
@mansr rightly said, it is possible to use bubbleupnp in your android phone to stream to the fire stick without needing to install anything on it. However they don't play well together, sometimes the songs don't advance, sometimes bubbleupnp takes very long time to discover the stick in its list of streamers.... All this happened with the free version, i don't know if the paid version is better. There are other android apps that like bubbleupnp that allow to stream to the stick but have the same problems of tracks not advancing etc., so i desisted with this approach.
- I tested several apps in the fire stick that allow you to cast or stream to it. Most of them are not for free, but some are. Most of them have issues or limitations that make them unsuitable or inconvenient to use for music streaming. However i did find one that works good for me. It is called "Mirror for Fire TV". It is for free, once you installed it and set it up, all my streaming apps see the fire stick and allow me to stream to it without having to do anything else. Maybe the only issue of this app that some people won't like, is that when you are streaming to the stick and you have the tv connected, the screen goes black. For me it is more an advantage, as i can still check the info in my phone and i prefer that than having to see it on the screen...
- When plugged to my amazon basics HDMI extractor, i can stream to the fire stick without any need for the tv, it works even when the tv is off, or even when the hdmi to the tv is disconnected. The fire stick + audio extractor work as a stand alone streamer, what i find very neat (for instance, when my kid wants to watch telly and i want to listen to music).
Now, the resampling subject:
- I was finally able to check the sample rate that the amazon basics HDMI extractor was outputting via toslink using a soundblaster x-fi HD that has toslink input.
- Unfortunately (well, it isn't really an issue for me, but most people here aim for bit perfection) the extractor (or the stick, or the apps, who knows...) resamples everything to 48kHz. I tested files up to 192kHz, everything comes out as 48kHz.
- As mentioned before, somehow Amazon Music HD skips this resampling and the same extractor outputs everything at 192kHz, regardless of what was the original sample rate of the song.
This tells me, if Amazon Music can, there must be a way to make the stick+extractor to work at higher sample rates, but i have no idea how... Actually, if someone finds out how to make the combo bit perfect, this would be a terrific ultra low cost streamer, less than half the price of a wiim mini or a raspberry pi + spdif hat.
Comments suggestions or ideas are welcome, thanks!