Dolby Digital sound drops out every 7 seconds

Hi all,

I got a weird problem when playing high quality videos through Kodi via my android box t95m.
Whenever I play a Dolby Digital file (say streaming video with Dolby Digital etc., or playing off home network) i notice that every 7 seconds the sound stuttuers/glitches/drops out (not sure how to best describe it).
Its as if someone turned it off for 0.001 of a second.

I have Kodi 16 audio settings as follows:

Channels: 2
Ouput: Optimized
Passthrough: Enabled
DD and DTS enabled receiver

Not sure what it could be the problem as i tested the speakers & av receiver with Blu Ray player and it works fine.

Any advice would be appreciated