Credit Risto Suominen and others on the Debian PPC mailing list for the idea of blacklisting the snd-aoa files. I just happen to have had a PowerMac G4 (Digital Audio) to test the concept on. Through trial and error I found the right file in /etc/modprobe.d to apply the blacklisting to. We had hoped that a patch to the installer would have been included in the Debian Squeeze release that came out in February, but it didn't happen, even with the newer 6.01 release. A bug report is filed at:
606984@bugs.debian.org. Pardon my contribution being so unreadable. I have since learned how to wrap text at 80 columns with Mac OS X Mail.
It works great on MintPPC 9 which is a much nicer, more complete implementation of xfce than the Debian version. The problem with the Debian standard GNOME desktop version is that while one can blacklist snd-aoa allowing the snd-powermac sound module to load and function correctly, when one tries to play an audio disk, Sound Juicer opens automatically and promptly crashes, crashing the File Manager as well. This is probably a separate issue, however. A lighter weight desktop like xfce is probably better on this old machine, anyway.
I continue to test the Debian daily-builds of the new Wheezy version, hoping to see some change. So far, not.
Thanks for the response.