If you where only having 16bit files in a session you should still use dither when bouncing down to 16bit because of the higher bit processing in the mixer... unless ofcourse you have forced the mixer to opperate at 16bit, witch is not a good idea.
I think im being misunderstood here. Let my try to clarify.
Suppose i have a LOGIC session with both 16 and 24 bit files within it. What would be the best way of bouncing the song to prepare it for mastering? My guess would be to bounce it to 24 bit WAV. From what ive read, there is no "harm" in converting 16 to 24 bit. So lets say i bounce this session to 24 bit, pre-mastering. Should i be concerned about any additional or abnormal sound quality downgrading when the mastering engineer goes down 16 bit to CD due to the two bit rates? Any advice would help on this matter. Thanx and take care.
I would convert the 16-bit files to 24-bit rather than vice versa. Make sure if there are different "qualities" for conversion in Logic (I'm not familiar with the program), that you pick the highest one. There shouldn't be any weirdness whatsoever with the mastering engineer going to 16-bit.