Just to understand, you are not sending a 5.1 movie or dts cd disk or multi chn to the CAP via the coax correct ?..also, see if your DVD player is set to PCM output, and also has the ability to output 96khz..if so, enable those.
When Selecting the co-ax in, keep in mind the output is via the analog outs of the CAP...
hope that helps..
Matt
http://members.rogers.com/mzn50/