I used to use the audio conversion tool that came free with DVD Studio Pro, A.Pack
, that does AC3 <> AIFF. I used that a lot, back with DVDSP 1.5 on OS9. It's mentioned on the DVD Studio Pro guide: http://www.digitalfaq.com/guides/vid...studio-pro.htm
I think ffmpegX does >AIFF conversion too.
I'd leave it as 16-bit. The AC3 is 16-bit, 48kHz, 192kbps.
WAV and AIFF is mostly just a system thing. Apple is AIFF, Microsoft is WAV. Same with AVI vs MOV.
Soundbooth for hiss reduction? Are you having any luck with that? I found Soundbooth to be more of a straight editor, severely lacking in filters. Even the freeware Audacity (which is also on Mac!) may be a better choice for you.
For that matter, Audacity may do AC<>AIFF, too. Never tried.
Beware of sample rate changes!! If you change from 48kHz to 44.1kHz, for example, it's not uncommon to lose audio sync on longer recordings. The re-sample is almost never perfect. Goldwave likes to default save as 44.1kHz, and if I don't pay attention, I'll mess up the new file. Even worse, if I trash the source, I'll have to start over. Learned that the hard way.