You record audio at 24bits and 96kHz or 192kHz even. Fission, the audio editor developed by Rogue Amoeba, isn’t capable of exporting your recorded audio at these high sample rates, but there’s a way around.
If you’re going to record audio in 24bits and 96kHz, you’re doing it for a purpose. It won’t be to save the recording in a compressed format at the same bit and sample rate. So, if you’ve recorded audio as an AIFF file in this high quality, you will want to end up with the same quality, even after splitting a file or changing the volume or fade settings.
In order to keep the same quality for a section of the file, you can just “Save as a Selection”. That will give you the same sample rate and bit depth, as well as the same file format. Fission will not touch your recorded audio, not even after you have split it up, normalized sound volume, or cropped the file. “Save as” will do the same: no downsampling there either.
If you want to downsample, you will use the Export option. The highest sample rate for recorded audio in Fission is 48kHz (DVD quality sound). This applies to all export file formats, including AIFF and WAV — which theoretically can be all the way up to 192kHz. The bitrate is also limited to 16bits for anything other than WAV or AIFF.
That leaves us with converting from one format to another. Unfortunately, here you can’t keep the same quality — not even when you’re converting from AIFF to WAV, for example. FLAC is limited to 48kHz/16 bit as well.