I had the same problem with my ZNP6. Never could figure it out. SO what i did was sent a signal from the coax into my Sony R300, which then passed a signal to my ZNP6 via the optical. Worked just fine. Maybe the coax was busted or is faulty in these cards.
To answer your ? though, I picked up an M-Audio Audiophile 2496 for my new setup once i moved. i bought it from ebay for ~$50, new, sealed, shipped. so far it hasnt given me problems and i have liked it greatly. hope that helps.