Hello Michael,
Thank you for being a PowerPress user!
Yes, PowerPress supports AAC as long as the files use the extension .m4a IF you are using another file extension, you may want to change how you export your files so they are saved in m4a format.
The most optimal format is mp3 and that is if you follow the tips linked here: https://create.blubrry.com/manual/creating-podcast-media/audio/mp3-mpeg-layer-3-tips/ AAC audio does have some limitations, albeit small, there is a small number of devices and software that will not play aac (m4a). The same rules apply for AAC as they do for mp3, the link I just shared should be helpful for AAC as well. This page explains the different audio formats in detial: https://create.blubrry.com/manual/creating-podcast-media/audio/audio-formats/
Do you mind explaining why you want to use AAC over mpeg-3?
Thanks,
Angelo
