Agreed that headphone damping isn't such a big deal compared to speaker damping. For interest, I measured the output impedance at 440 Hz of the S3 using 10 ohm resistive loads on both channels and a scope. I did this at 2 volume slider levels on Music Player (10/15 and 12/15). With this 10ohm load, clipping distortion shows at 14/15. The S3 output impedance is calculated simply from the voltage divider compared with the output voltage with open load.
The result is Zout(400Hz) = 2.7 +/- 0.2 ohm and the same at both volume levels tested.
Also I did a spot check of the output spectrum using RMAA spectrum analyzer (with 22 ohm resistive loads and at a volume of 12/15 ..pretty loud) and it looks pretty clean. The source file was a 16bit/44.1kHz pure sine wave wav file at 440 Hz at almost full digital level (-0.2dB) :
S3 Spectrum for 440 Hz Tone
The result is Zout(400Hz) = 2.7 +/- 0.2 ohm and the same at both volume levels tested.
Also I did a spot check of the output spectrum using RMAA spectrum analyzer (with 22 ohm resistive loads and at a volume of 12/15 ..pretty loud) and it looks pretty clean. The source file was a 16bit/44.1kHz pure sine wave wav file at 440 Hz at almost full digital level (-0.2dB) :
S3 Spectrum for 440 Hz Tone