This stuff is insane. Nothing is fully compatible with anything...even from the same company. Amazon Music HD Ultra isn't even compatible with their Firestick 4K. The music stream comes in at 24-bit/96Khz but the Firestick down-converts it to 16-bit/48KHz. Not because the Firestick doesn't have the requisite hardware for FLAC decoding but because the firmware team didn't make full use of the hardware. What's absolutely laughable is customers are paying for HD Ultra but have no clue they aren't getting Ultra at least on their Firestick 4K. According to customer support, I am the first who has complained of this.
BTW, I can stream Amazon Music to the Air via Bluetooth but I have no idea if it's aptX HD. The HD Ultra definitely sounds better than standard quality but how much better in terms of bit depth and sampling frequency, I have no idea.
On my Firestick, I can't hear a difference between a song in Amazon Music Ultra HD and Spotify premium. Amazon is CD quality or better and Spotify Premium is at the top end of mp3. But I can't hear a difference on the Actives.
Last edited by Mojo; 10/20/20 04:11 AM.
