Bit Depth and aac *quicktime aac* Options

[Mix3dmessagez]

I have some needledrops, 24/96 *forget the hdtracks now cause i'm learning some new stuff*

andn i use izotope src and mbit to resample and dither to 48/16

i've apparently learned that there is no depth in aac *bit depth*

and i'm curious, is it better to simply just leave all my drops at 24 bits so when encoded for portable use it will be used?

In comparisons i've done when dithered and when just left normal the dithered files *when both are encoded to aac* result in slightly larger file sizes and higher bitrates *of maybe 1,2 o even 3 larger, than when converting from 24 bit sources.

I figured with that being the case it must ignore bit depths and always use 16 bit anyway so I left it at that.

If any experts could provide me insight it would be greatly appreciated as i'd like to know which is better and how much difference it makes *not in terms of listening tests but scienticially*