Since there is no entry on K-Mix on GP, this is going to be an on-going snippets of review and comments. Some initial thoughts using with iMac Retina 4K, 21.5 inch, 2017, macOS Sierra 10.12.5. 1. Firmware update to 1.3.5. The process was very easy. All I need to do was press one button inside the K-Mix app as the app handled the downloading and updating automatically. After the firmware update I was prompted to restart K-Mix. This is the one of the easiest firmware update I have done. 2. I upgraded from Focusrite Scarlett 6i6 1st gen. When 6i6 was connected to my computer, the volume control from my computer keyboard and on-screen slider were disabled. So the only way to control the volume was using the volume knob on 6i6. But the K-Mix works with the volume control built into the computer keyboard as well as the on-screen volume slider. Very nice!