Cable tv music analogue or digital?

I was trying to improve the quality of the sound coming from my cable tv box, sometimes I like to listen to the jazz station. I ran a regular rca jack from the analogue outs on the cable box to the analogue inputs on my pre-amp, the sound is ok, but I wanted to improve the sound. so I ran a cable from the digital coax output on the cable box to the coaxe input on my Cary 306/200 cdp/dac and then into the pre-amp. guess what, no audio signal coming from the music channels but I do get an audio signal coming from the regular tv channels. Is it possible that regular tv signals are broadcasting in digital but the music channelis still going out in analogue? what else could it be.