Some portable amps run their gain stages at a lower voltage when powered from the internal battery, but permit higher voltages that can be supplied from an extenal PSU.
Per the datasheet, OPA1612 can tolerate Vs as high as +/- 18V, but THD+noise is lowest when Vs is +/- 15V.
Will the X5 allow a higher Vs than +/- 6V when using an external power supply?
Thank you - it looks like a great product, so far!
Update: I realize this is a DAP, not intended to drive power hungry headphones. Line Out can be used for an external amp, if I want. :-)
Edited by zilch0md - 10/28/13 at 8:59pm