Did it ever produce sound when using the SPROG? I had a similar problem with my Life Like P2k factory installed QSI decoders when I tried to run them with my SPROG 2, but when I took them to my LHS, they worked fine, sound and all. At that point, I stopped worrying about it, since I bought the SPROG mainly to do programming, and for that, it works way better than than my Digitrax PR3, which was replaced with a brand new one (still sealed in the package) by Digitrax.
Bill in FtL