I didn't find audio out of sync issue on my MeCOOL BB2 Pro (S912 3GB RAM) even with danxc's 1st 8.2 release. Will update with current release and test again.
With Leia build (wrxtasy) on the same box, audio out of sync issue happened from the very beginning of playback and getting worse and worse. Similar situation happened with Raybuntu's Leia build on Odroid-C2 (tested up to leia5) as well. 720p 8-bit HEVC contents are less susceptible to sync problem while 1080p 10-bit HEVC are the worse. It seems there is no hw acceleration for playback at all, or at least not sufficient.
All my video contents resided on NAS connecting via ethernet using either Samba or NFS protocol.