Would need to know a step-by-step on how to do that. I do have RCA>Stereo-mini cable.
This would be my basic guide:
1. Hook CD output to recorder input.
2. Set recorder to 24/48 (or 24/96, whatever you usually use) and unity gain
3. Play song on CD player and hit record on recorder (preferably use a DVD-A or SACD source disc)
4. Repeat for all 3 recorders, and maybe use a couple different tracks/styles of music
5. Examine audio files to ensure that they peak around the same level (they should if recorders are set at "unity gain")
6. Post the files here so we can listen and judge!
This really helped me compare the R-09 and R-09HR when I had both those recorders (and helped me ditch the R-09). I'm most interested in the M10 vs. R-09HR. Of course, this only compares the line-in performance.