If you are going to record more than 3 hours and 22 minutes, extract to FLAC format. If the audio duration is less than that, WAV format will also work.
So you should be able to use the same 320kbps settings without any degradation.
…I’m not sure you can create 320kbps AAC with Audacity. You might need to make a WAV or FLAC first, and then use a 3rd-party converter (like Kabuu Audio Converter) to make the AAC file.
Since AAC is a compressed format, recording it directly into another lossy format like MP3 or AAC can lead to quality loss. Recording in WAV or FLAC instead. This ensures you capture the stream’s full quality. You can convert the recording to AAC later if needed.
I’m just intending to record the AAC stream to archive for future listening, rather than create a new stream.
Sounds like FLAC is the way to go as with my brief tests files are about 50% of the WAV file size.
I will have a look and a listen to the 100 pass recompression link.
cheers