[noggin]

Popcornmix - here's an update on the playback performance of a Pi 2 with the file I PMed you a link to :

No audio pass-through
OMX Player - Sync to Display - very occasional
OMX Player - No Sync to Display - frequent
MMAL Acceleration - Sync to Display - occasional
MMAL Acceleration - No Sync to Display - frequent
(Sync to display method, when enabled, was Resample Audio)

So Sync to display improves things, but in all cases there are still issues IMO.

Audio pass-through
All the above scenarios are close to perfect - with possibly the odd stutter. No obvious difference between them.