Tip of the day:
In answering a question in another thread, I realized that there is a really simple workflow for importing AC-3 files directly into Vegas, without any video, and without external tools. It does require DVD Architect.
1. Open DVDA.
2. Drop the AC-3 file directly on the main menu of a new project.
3. Immediately prepare the project. Since there is no video, the project should prepare in just a few seconds.
4. Go to the prepare folder, and in the VIDEO_TS folder, find the VTS_01_0.VOB file and drop that onto the Vegas timeline. Ignore or delete the video track that gets created.
Voilà !