I fought with this device for quite some time. My first line of trouble shooting, was that I had some ground fault noise in my system. I had this controller connected to my pc using the mini klinke plug, and at various random times, i would hear a hissing/scratching noise coming from the speakers. It was not very loud, so I took my time trying to figure out where the noise was coming from. It couldn't be from my brand new controller... Or?
I decided it was the connection to the PC, so I bought a small in-line DAC from the same brand, and used the optical audio output from my PC. Problem solved!! Or?
A few days later the noise reappeared... Randomly. Now, after a very long time I have determined that there is some faulty connection happening with the mute button. When tne noise begins, i can just wiggle the mute button, until it goes away. And crazy as it may seem, I cam also wiggle the mute button, and make the noise appear.
I had imagined that a product made by Thomann would have better quality control... Granted, it was inexpensive, but still... Not so cool.