I did a comparo between the two, using my favorite Pink Floyd Album WYWH. Needless to say, I know the album by heart. I did an ab comparo, and really couldn't hear a difference. On the iPhone, I used the stock player no EQ, and on the SGS3 I used PowerAmp with no EQ. All I had to do was boost the Tone controls on the SGS3 about an 1/8 of a turn up, and I felt that the sound was very similar. I've been told the 3Gs is one of the best players for SQ, and the SGS3 leaves something to be desired. But if all it takes is adjusting the tone controls a little, to get better sound, why not. The 3Gs had boosted bass and clear highs, and with the adjustment to the SGS3, the output was similar enough that I didn't mind using my SGS3 as a player. I currently use my 3Gs in the truck to play tunes through my stereo, and use my SGS3 as a portable.
Are the negatives of the SGS3 easily overcome with a little tuning, or is it as bad as I've been led to believe, and I have tin ears? All testing was done with Audio Technica CKS77 IEM's.