Connecting cable box RCA digital out...

I'm trying to connect digital out of cable box to my new Mytek 192 DAC, but only crackling sound is heard.
I figure that I can only use multi-ch receiver or processor with digital input, but is it possible for 2ch DAC?
What setting is your cable box using to output it's digital
signal. It's probably Dolby 5.1 and the Mytek doesn't like
that. You would need to go into the menu of the cable box
and see what settings are available.
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Marakanetz: My question is does TV sound significantly better through the DAC vs going directly from the cable box to a preamp or integrated amp? I understand that a good DAC “should” sound better, but I’m wondering if it does in the real world, i.e., I imagine the sound coming in from the cable company is compromised enough that it may not make much of difference whether one goes directly from the cable box or from cable box to DAC to pre/integrated amp.

Thanks for any thoughts you have.