Audio flickering on and off when watching On demand.

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This does not happen when watching normal live television.  Nor does it happen when I'm streaming Netflix through my ps3.  We've had fios for about 6 months, prior to this we had comcast and I did NOT have this problem and I have the same audio setup.  From the cable box I'm going via digital coaxial, I've also tried a optical cable, into my Mcintosh D100 DAC then into my McIntosh amplifier.  

I did contact verizon a while back and was told to restart the modem and unplug everything for a minute which I did and the audio still flickers.

I'd really like a solution as its unbearable.