No sound w/ digital tuner under Win7

A newby here. Just installed a SiliconDust HDHomeRun Digital Tuner a week ago (Single Network). Using a digital ant. The pgm. finds a doz. or so channels w/ terrific pictures but no sound (sound is working via misc. 'net connections). Signal strength & quality are above suggested minimums and quality at 100%. Using Win7 Ultimate w/64bit, XFX Radeon HD 5870 Video Card, 12GB DDR3. Two home computers linked through a HP EX490 MediaSmart Server. I posted a note on the "" on 2 Jan, but received no responses.
Any help would be greatly appreciated. Thanx.

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