I don't get this product.
I think Samsung has learned their lesson with the Galaxy S2 and the Yamaha DAC mishap, so just as the first Galaxy S phone from several years ago their new phones come with a Wolfson DAC (International version) OR something or other by Qualcomm in the US and other specific markets that is no slouch either.
GSMArena is one of the very vew sites (if not the only one) that actually digs a little deeper into the audio quality of mobile devices in their reviews and the Samsung S3 and S4 post very good numbers. In the past the iphone was king here, at least judging by the measurement numbers.
But my point is I think they sound excellent. (Some Nvidia Tegra 3 Phones sounded poor, Realtek DAC badly implemented, see HTC one and the improved HTC One+).
I believe a portable device should be coupled with a portable headphone which is efficient enough to get the best out of the combination.
Personally I wouldn't want to run huge 250ohm plus headphones on a portable rig. I would attach it to home audio equipment.
So I guess im just not that much of an audiophile to see this as a good investment. I mean AMP/DAC costs more than the phone itself.... That said I think it looks beautifully sophisticated, well engineered.