Your K-Mix might not be the culprit here. If you are using your K-Mix on Mac OS X 10.9-10.12, you may get distortion, dropouts, and gradual degradation of audio coming from your computer due to a bug in the operating system. 

These symptoms may appear in isolation -- you may only get degradation, you may only get dropouts, or you may see all symptoms at once. These issues can come and go, with little to no predictability.  They can vary in frequency and severity from system to system, and have been reported when using other audio devices as well, even if this isn't apparent with a quick A/B test. 

The appearance of this issue has ben lessened on Mac OS X as of 10.12, and in some cases it disappears completely. If you experience these symptoms on one of the previous OS versions we recommend updating to 10.12.  If that is not an option, or if the issue persists, there are a few things that you can try to increase your chances of stable performance. 

• Start with a fresh boot of the system.
• Turn Wi-Fi, and Blue Tooth off. Network communication can sometimes cause issues with audio processing/playback.
• Close all other applications other than your audio application. 
• Turn off AppNap. You can do this for individual applications, or globally. We recommend turning it off globally. 
• Make sure you are connecting the K-Mix with the supplied USB cable, and that it is getting sufficient power (if using a USB hub, make sure that it is powered). 

Resetting the CoreAudio Driver can also help. You can do this by changing the sampling rate of the K-Mix in your Audio/MIDI setup, or inside of your Audio Applications audio preferences/settings. You can also do this by changing the buffer size, or by power cycling the device.