I'll be honest, I don't have enough information about XACT to answer this question, but since it's a standard Audio system developed by Microsoft, it stands to reason that it should be relatively compatable with DGDK. I'll admit, it may require using some form of file format or passing of buffer data directly into DirectX for playback using the various functions, or maybe some DX function call to convert, but as said, I'm not that ofey with the toolkit.
My general reason for answering is that because it's an MS DX product, it may be possible to use it with DGDK.
Paul.