PC toDAC Connection

Look for something like the Behringer UCA-202 (it's a USB/Digital audio adaptor).

M-audio Transit is another option $80

Digital audio in/out to your pc

Purchase a LynxStudio PCI card; has all the outputs on it you'll need to connect to any DAC

For a 25 foot run I'd use a good Toslink.

Thanks all of you for your advice. Where can i buy such a long cable and how much would it cost?

B & H Photo may have it. Can't help the price ranges. Their tech support is usually very helpful. With newer technology, I ask for someone who knows about a specific application, first. They may offer you further options, too.

www.computeraudiophile.com may help.

amazon has 25' digital optical cables for as little as $15; accessories4less and mycablemart should also have 'em. any well made cable should do the trick for you.