I just do not see the point of external DAC units. A DAC has one job and due to how digital audio works it's very very difficult to get it wrong. Meaning that whatever inbuilt DAC your device already comes with is more than sufficient for anyone's needs. Just seems like a massive scam to me, you literally may as well flush your money down the toilet. Any alleged improvement in sound would have to come from audio signal processing (no!) and not from the conversion process itself. And don't get me started on fancy HiRes formats. There's excellent reasons 16-bit 44.1 kHz was originally chosen as the CD standard. You just don't need "more", in fact higher formats are only likely to introduce unwanted artefacts. Do your research before you shell out your hard-earned cash on an expensive but useless DAC.