I do not have any experience with the Stainz, but I have used LGB built-in analogue sound modules that were taken from LGB Uintah Mallets and have used them in conjunction with a DCC decoder (but not wired to it) in Bachmann 'Annies'.
The LGB analogue sound units are pulling power from the DCC track and work fine with a hall sensor on the loco wheel as a chuff trigger, whilst the loco uses the DCC decoder to operate motor and lights.
It seems that a lot of the LGB analogue sound modules, fitted to their locos will also work on DCC 'provided that there is a chuff sensor to tell the sound unit what speed it is going at (but not a motor load dependent sensor which would just see the DCC voltage and only give one level of chuff)