Like I, and many others, have mentioned:
- Line out dock (LOD) to mini-jack/plug DAC/amps only bypass an iDevice's audio DAC (FiiO E17 for example). The external DAC/amp only acts as an amplifier at this point. These types of DAC/amps are generally priced at < $250
- LOD to USB DAC/amps bypass both an iDevices audio DAC and amp (Fostex HP-P1 for example). The external DAC/amp then does all of the audio processing. These types of DAC/amps are generally priced at the $500 point.
- mini-jack to mini-jack merely provides double amplification to your audio signal
Thus, unless the Galaxy SIII has a line out option, it's not worth buying anything for it really. If you can plug in headphones and hear music, it has both a DAC and an amp.
The E7 is good as an external computer soundcard (DAC/amp), but otherwise it will just act as an amp.