Official comment
I listened to the audio a couple of times, and I hear two things...
1) There is an audio crackle which sounds like a buffer underrun, typically caused by a low buffer size setting and another application suddenly requiring more system resources, meaning rekordbox can't provide a consistent stream to the audio device. You can try increasing the buffer size, and disable any other background services or applications which may consume resources. Open your process monitor to see what may be using CPU cycles when those audio issues occur.
2) There is interference on the USB connection; this is almost always because of poorly shielded USB chipsets in the computer. Unfortunately there are only a couple of ways around this - and one of them is to use a different computer. The other is more of a work-around, and there are a couple of things to try here. First try using a different USB port which may offer better electrical isolation. If that doesn't work, a USB cable with a ferrite core may provide some blocking of the interference. Another is to try an externally powered USB hub. Some of them provide electrical isolation which may eliminate the problem, but not a guarantee. The last ditch option is to use an isolation connector which uses a transformer to "disconnect" the direct electrical path between your computer and the DJM - something like this.
