[pwjazz]

One difference could be that testing the LG V20 required me to play a pre-recorded frequency sweep through a media player on the phone (USB Audio Player Pro). I'll try feeding the NX4 via USB from the LG V20 and UAPP and see how that looks.

Here's the result of driving the NX4 from the V20. It looks just like the NX4 driven from my Mac and doesn't show the initial dip from the V20's DAC, so the difference is not due to the pre-recorded frequency sweep or UAPP.