New power supply didn't change the high pitch tone for me, nor did a cheater plug. Loxjie still has not contacted me regarding getting a new unit. It would be perfect if not for this issue.
I do, Ive also noticed that it seems a little louder in the left channel than the right. I contacted Loxjie to see if I could maybe try a new unit
In the meantime gonna see If I can try a different power supply
Mine is silent when speakers are the selected output. When I switch to headphones the high pitch noise appears. I am using the D30 as a preamp into it too, but the issue seems to be coming from the a30. I tried a cheater plug too and that didn't help.