I got a Firestick 4K today. It has up to 24 bit/192KHz (the absolute ultimate which is also fully supported by my Onkyo) audio support with up to Dolby Atmos. It supports all popular video and audio formats including FLAC. When listening to Spotify Premium, it's like my entire system got a huuuuge audio upgrade over my previous Chromecast Video. Now I'm gonna try Amazon Music Ultra HD.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated