okey, i'll try to use ipowerx for few days before i reported again

Yes i think using battery is more portable and cleaner without any interfaring noise from external power, which are usually dirty (with common adaptor 5v or from usb-pc) my early expectation buying ipowerx, this could give clean very low noise power to headphone amp and make sound no different...

thanks Sphere57 for explanation. i using headphone amp powered by 5v dc, when i plugged into ipowerx the sound become a little aggresive and harsh/metalic, compared when its plugged off using internal battery warmer, smoother and more natural. Is the power from ipowerx still not clean enough...

Hello IFI Audio , i just buy 5v ipowerx... and i want to ask what the use of white adapter that called reverse polarity, how do i know when i can use it?