To be honest, I don't think this definitively answers the question (although maybe I am missing something). You still need to know two numbers, I think: the voltage that the test signal generates at the CD player's line-out and the voltage corresponding to 0 dBFS on the line-in of the M10. Then you could figure out the level on the M10 that corresponds to the same voltage coming out of the CD player...
I read somewhere that 0 dBFS corresponds to 1 Vrms, but I can't for the life of me remember where I read it (and can't find it again either), so take that with many grains of salt. And there is no real standard for CD player line-outs, so that can vary from player to player.