What a shame, but thanks for sharing your experience. It blows my mind that anyone would design a cd player that doesn't have gapless playback. I almost purchased the Tangent CD II player a couple of years back then noticed reviews mentioned there were gaps between tracks, so immediately crossed...
The Cambridge Audio Dacmagic 100 has 2 coax inputs:
https://www.audiosciencereview.com/forum/index.php?threads/cambridge-audio-dacmagic-100-review.12201/
There is the new Loxjie A40 as well, though it looks like it performs similarly to the SMSL AO300 with HDMI Arc. There is also the Harmon Kardon Citation amp, but there is a thread on here reporting various issues with it.
I ended up going for the Sonos AMP, as it seems be generally well...
Its a shame HDMI ARC is so poorly implemented on this and the SMSL AO300, its a bit of a deal breaker for me. Hopefully Wiim have done a better job with their new amp.
The Plex client on windows can do bit-perfect. Plexamp for Windows doesn't have a setting for this - i think it's just IOS, Mac OS and Linux that do. I don't think Tidal played via Plex is bit-perfect though.
SMSL C100 for £79.20 (using voucher), with next day delivery:
https://www.amazon.co.uk/gp/product/B0BNFZ75LJ/ref=ox_sc_saved_image_1?smid=A2XL2OZZCZEZ5B&psc=1
I quite liked the original Mx3, but then i added a subwoofer to my setup, and they didn't get on. A loud thunk from the sub, when the amp was powered off, and then it shut itself down after i connected my headphones (which was fine before i added the sub). I saw similar reports from other users...