I have m4as that I rip using the Music Media Helper and they play back no issue on Windows' built in Media Player app. I find that I even have less of that annoying silence at the beginning due to the handshake. And tracks play back gapless so I think it is the best approach currently to playing TrueHD Atmos m4a on PC.I'm talking about TrueHd Dolby m4a (24/48) and the difficulty most PC players and DAPs have in reading it. Why this limitation?
By the way, what process do you use to get those Atmos lossless m4a? Just out of curiosity.
EDIT: Sorry, I miswrote. I'm playing them as mka, not m4a. Better to just use mka as others have said here that m4a may not play gapless.