AIFF > ALAC > AIFF = truncated bit depth

I've always kept my library in full fat AIFF, having tried ALAC before and deciding to stick with AIFF. With Audivarna memory play equalising (for me) any playback differences between the two formats i've decided to start to convert my library to ALAC to free up some disk space.

One question, in the past when i tried this and then converted the ALAC files back to AIFF, my 24 bit files got truncated to 16 bit - using XLD to do the conversion of the ALAC files maintained the original bit depth. Is this still the case with iTunes ?

James