If you are computer savvy or have a child in college this link may assist you with the decoding. There are also other links in bedded that might help. If you are looking for a hard wire device I suggest going to SamAsh and looking in their Home Studio department. They have all kinds of digital conversion devices.
Free-Codecs.com :: Download AC3 Decoder 1.2.6 : AC3 Decoder is a convertor for AC3 files and unprotected VOB format files to Ogg Vorbis, MP3, PCM, WAV, WMA