When watching a video (MKV video with AC3 audio) and changing subs (usually setting subs to Dutch

) I lose audio sync on S/PDIF.
Audio on BOSE S/PDIF lags a second or so, compared to HDMI audio on TV. (see footer)
Seems to happen "all the time" when changing subs, also (and always) when pausing/resuming.
I've read some posts about this and how to workaround, but for me stopping/resuming works best!
Is this a problem with the MED500X2 or has it todo with the interaction between MED vs BOSE?
My old TVIX M-6500A never showed this problem....
Can I resolve this problem somehow? (without investing

)
How come this problem shows anyway?
Tnx in advance