I have pushed for that for a while now.
I can only think that it is because "Bit-exact dither" (RPDF) will not dither the output under certain conditions.
Formats like MQA probably don't play correctly if TPDF is selected, even if you have no DSP enabled and volume is at 100%, while it probably works with RPDF under those conditions.
This is because Media Center doesn't seem to actually disable dither if no other DSP is being performed. Doing that will have no effect on audio quality, but can affect encapsulated formats.
I see. I've tried both now using the convert file DSP window and the option checked to use DSP, with just volume levelling applied. Converting from 24bit 96khz to MP3 320 CBR and then tested in the car. I can't tell any difference. My ears, MP3 sucks, not great stereo electronics and speakers in the car. Or all of these and more.
Do yourself or anyone else here have any good tips for creating a flash drive of MP3's from high quality flac's for the car. I've found 'Anerty's Lair - DriveSort' very useful for re-ordering albums and tracks that don't play nice on the actual flash stick (not the PC). And of course very well done tagging using JRiver, once I figured out the file setting to embed the cover art into the file (MP3 or Flac).
*idea, maybe a prompt (tip bubble) whilst in the tagging section and hovering over the cover art that you can embed the cover by turning on that option.
I think I have a pretty good process so far, convert flac to mp3 using convert format DSP with just volume levelling on, to 320 CBR. I've had to use the DSP parametric EQ to raise some album volumes JRiver just didn't bring up enough, but not many.