I had a lot of problems with 50k and 100k dual potentiometers, they didn't work. I connected it in a lot of ways but still nothing. Now I connected them like on the picture bellow (I did it also on the breadboard to show connections). When I am connecting it to Fiio K3 one channel is working, in second one every diode produce light all the time. I also tried on my tablet and there one channel work a little (few diodes produce light all the time, few move) but second channel didn't work (all diodes produce light all the time)