ok had a brief listen in with/without the amp anyway.. I don't have Voodoo installed either, which is supposed to improve SQ on the SGS, not sure if this will apply to the Galaxy Player, also bare in mind the Galaxy Player will most likely have different audio hardware to the SGS, as well as many other differences, which could improve things as a media player.
With both players on the loudest and every setting to neutral/default: the m6 had a slightly higher volume, the highs were ever so slightly crisper, maybe a little too bright. Increasing the treble on the SGS almost matched this, but would sound slightly metallic if increased by too much. Un-amped the M6 drives my M50 really well, particularly the bass, even at maximum, does way better than the SGS, which also requires decreasing the preamp and in effect the maximum volume.
Amped the M6 does even better, and significantly better than the SGS amped. But overall the sound quality of the SGS using PowerAMP is still very good, and the EQ and tone settings are very customizable.
Thanks for asking about your M3's SQ though, it made me pull out this little gem which I will probably start using now and again.