Does anyone know of a "black-box" DD decoder that is commercially available?

I've been looking for a "black box" that will take a DD 5.1 coded SPDIF
input and convert to 6 line-level analogue outputs, and have failed to find
one. Plenty of "Surround-Sound Amplifiers" (complete with power-amps, etc.)
around, but that's not what I want.

David.