Pro Tools HD For Mastering, 24 bit Playback Dither?

[rentedroom]

I'm looking for a purely technical answer to these questions:

Subject: Playback of 24bit files on Pro Tools HD 8.0 for mastering

I have read other discussions that the "Stereo Dither Plugin" is needed for Pro tools HD 8.0 because of 48-24bit truncation, but on some software like "Soundblade" you don't need to dither 24bit files unless you make any level changes, fades, processing, etc.

My question: Is "Dither" or the "Stereo dither Engine" needed if you are ONLY using Pro Tools HD 8.0 for playback with NO processing, panning or level changes, fades, etc. ?

&

Is processing happening if you are playing back stereo material on a "Stereo Channel" Vs. "2 mono tracks"

I've looked in the manuals and other forums and I have not been able to find this out. It discusses that dither is needed but not specific if PRo Tools HD 8.0 is being used just for playback.

[minister]

Originally Posted by rentedroom

My question: Is "Dither" or the "Stereo dither Engine" needed if you are ONLY using Pro Tools HD 8.0 for playback with NO processing, panning or level changes, fades, etc. ?

PT uses the benign TPDF dither.

All I/O are 24 bit. It is not just the plugin hand-off, the mix engine if 48 bit. Any bussing internally goes through the mix engine.

If you are just doing playback with no plugin's and going straight out to a physical output (no bussing), then what does it matter which mixer plugin you use? The Stereo Dither Mixer won't touch 24 bits, but neither will the non-dithered mixer.

[Rob_Rose]

IMO Dithering is never a good Idea but obviously needed in some cases one really needs to understand dithering to understand this isse! I undersand the Trunc issue but when you are going through the 48 bit M.E. what does it matter really when you have 24 bit I/O's? Dithering only takes away information where the computer deems it to be not needed. Do you want the system to determine this or you the mixer?