I have the combo of iPower with the Gemini cable feeding to the iDAC in my library system, w/o the iPower and Gemini cable the sounds is ok, with the combo the iDAC is pretty good. You may want to look at the AQVOX usb power supply.
All computers, even run in battery mode, generate too much garbage on their DC lines, including USB. There are some DACs that are less prone to that, those where the USB-chip is powered from the DAC internally. IMO the NAD M51 is not.
All computers, even run in battery mode, generate too much garbage on their DC lines, including USB. There are some DACs that are less prone to that, those where the USB-chip is powered from the DAC internally. IMO the NAD M51 is not.