I originally purchased a Zidoo Z9x about 2 months ago and only found out about it when I saw this post when I had the exact same problem. uHaving been a long term kodi user I went down the path of using ZDMC which works really well for me. When I originally bought the Zidoo I installed 6.3.75 firmware and was able to play The Beatles Abbey Road Atmos M4a files that I had ripped through ZDMC. With the recent updates both .88 and .92 it has made it unplayable and has continual drop outs. Not sure if things have been impacted on the ZDMC through the firmware updates recently. Would like to get this working again.
Same issue with Music Player (which ZDMC must use for playback) since the firmware update to 6.3.92 This has been raised in the 6.3.92 beta firmware thread and confirmed by @Nice Monkey that Music Player was improved/altered in the latest release. Hopefully Zidoo can find what was changed and revert this part, so that m4a files can be played again.