I recently started recording in 24 bit, but no pk files were created in adobe audition/cool edit. Is there a switch for 24 bit, or does aa/cep only do pk files for 16 bit?
IME, CEP only builds PK files for 16- and 32bfp, not 24-bit.
AA/CEP has two different "workspaces" - a 16-bit workspace in which the s/w uses 32bfp precision for processing and then dithers back down to 16-bit automatically as part of the processing, and a 32bfp workspace (which is used to open 24-bit files) in which the s/w uses 32bfp precision for processing and then leaves the results of that processing at 32bfp for the user to dither later.
Ideally, one should dither only once to minimize quantization noise. Performing multiple edits to a single portion of a 16-bit file within the 16-bit workspace will result in multiple transitions between 16-bit and 32bfp, thereby increasing quantization noise. So if one's performing multiple edits on the same portion of a 16-bit file, open the 16-bit file in the 32bfp workspace. (Options | Settings | Data | Auto-convert all data to 32-bit upon opening.
Note: this doesn't actually "convert" anything - the data is still 16-bit until one performs an editing operation. Only upon editing does the portion of the waveform edited become 32bfp data. If doing this, leave all edited portions of the waveform as 32bfp until all editing is done, then dither the entire file back to 16-bit before tracking.)
AA/CEP by default opens 24-bit files in the 32bfp workspace - there is no native 24-bit workspace (else we'd run into the same issues as the 16-bit workspace in which each edit transitions back and forth between bit-depths resulting in increased quantization noise). But again, the data is still 24-bit even though it's in the 32-bit workspace. The first edit operation produces a 32bfp result, and all subsequent operations will also produce 32bfp results - there's no dithering and re-dithering like in the 16-bit workspace. When done editing, simply dither to 24- or 16-bit as desired.
I hope to put together an AA/CEP guide in the next couple weeks that lays this out more clearly.