Approx in the same section as other manuals, on page 66. The section is Explanations right after Specifications. It is an entire paragraph, with Heading About the DSP TYPE-S for ATRAC/ATRAC3. The manual is copyright 2003.
I just bought a MZ-S1 (as a backup to mz-n505). Yes in 2005. The packaging came with SonicStage. Listening to this compared to the 505 I noticed the sound was much better. Strange I thought since both are Type-R What I found interesting was in the manual that came with the MZ-S1 it says This recorder supports DSP TYPE S. on page 66. Looking at an older manual for this unit on this page http://www.minidisc.org/part_Sony_MZ-S1.html the same section says it has TYPE-R only. Perhaps this is a mistake in the manual, anyone who has this manual can you check and report back?