Let me first make sure we understand each other: Sony takes the FF400 output, which is 24, and invariably interprets it as being 16.
I did several tests and checked them with DIGICheck. From my web-research it seems that the Channel Status Data contain information about the word length also in consumer mode, not only in professional mode as stated in the DIGICheck Help file. But it is in a different position, and I'm not too sure where.
What I can tell you though, are the results of my tests. There was a strong correlation between the word-length, as identified by Sony, and what you call "Reserved byte 4" (leftmost) in the Channel Status Display of DIGICheck.
The 24 bit output of FF400 has a constant value of 00 (for all the bytes 4-13 and 14-23), whereas my other sources put varying values in byte 4:
- computer sound card (24 bits): 08 Sony sees it as 24 bits
- newer DVD player (16 bits): 02 Sony sees it as 16 bits
- older CD player (16bits): 00 Sony sees it as 16 bits
So, here is my interpretation of the results (total guess, I'm no expert):
08 : 24 bits
(04 : 20 bits ?)
02 : 16 bits
The default value of 00 is being treated by Sony conservatively as 16 bits rather than 24.
Could this make any sense? I hope it helps you at least on the way towards a solution.
Maybe I could test a patched version which constantly puts a 08, to see if this pleases my recorder.
If positive, an additional option on the main tab of the FireFace driver might be an easy solution.
(I don't know if you need 00 at all, maybe for devices that like to detect the word-length themselves?)
Louis de Stoutz