Help! Gain pumping when converting to AC3

[dla]

I'm a first time DVD author, and I'm getting gain pumping when converting my AIFF audio files to AC3 using A.Pack.

I don't want A.Pack to change the audio at all, and so I followed the DVD Studio Pro manual.

I set compression preset to none, dialog normalization to -31, data rate to 192kbps, audio coding mode to 2/0 and target system to dvd video.

The audio consists of loud music on top of the sound of skateboard wheels.

Any suggestions as to what I'm doing wrong would be greatly appreciated. Thanks.

[setarip]

If, as I presume, you're referring to Mac-related activity, you'd probably fare better posting your question at a Mac-specific forum...