The results are impressive on paper, which may be why so many people were talking about the K-Mix. One might not expect much out of a unit measuring 9.3" x 6.4" x 1.6", but the K-Mix boasts a respectable ten outputs and eight inputs, two of which are XLR/TRS combo jacks with phantom power. Thanks to some innovative engineering, the K-Mix runs on USB bus power and features custom ultra-low noise preamps that reportedly use nearly 100 times less power than their traditional counterparts. This preamp development work was a significant area of concentration for the KMI team. McMillen mentioned in interviews that it took more than eight months of design and testing to meet the efficiency and quality standards they set for themselves. Leaving aside the K-Mix's ability to function as a standalone mixer and control surface, many buyers looking for a regular bus-powered audio interface would be satisfied by its input/output spec, size and preamps.
The other sections are similarly kitted out. The K-Mix provides a digital mixing engine with an onboard DSP platform, which includes a three-band EQ, noise gate, compressor, rumble filter, and reverb send for each of its eight input channels. The K-Mix's ten outputs are divided into the main output bus and three separate aux busses. You can set different levels for the input channels by first selecting the bus and then using the touch-sensitive faders—it's worth noting that the only difference between the main bus and the aux busses is the DSP processing, which is only on the master bus. There's a headphone output that can be assigned to monitor a bus, but it can also be used as a separate output when the K-Mix is used as an audio interface. I only encountered trouble with mixer mode when dealing with stereo sound sources. While the K-Mix allows you to group volume faders with a software editor, there's no way to link channels for stereo processing, which is a fairly standard feature on other digital mixers. That means you have to manually adjust the pan, EQ, compressor, and gate settings for each channel independently, which is certainly a bit of a drag, and the nature of the K-Mix's touch controls make it nearly impossible to get the settings for two channels to match perfectly. However, KMI have told us that they've a new update on the way which will rectify the lack of stereo linking.
These touch controls form the heart of the K-Mix's third role as a control device. There are three banks of MIDI controls available in MIDI mode, accessible by holding shift and pressing the Record/Play/Stop buttons. Each MIDI bank lets you send MIDI messages with the faders, rotaries and buttons on a MIDI channel assignable to each bank. A multicoloured LED shows the last value sent by the controller, and you can customise the MIDI CC numbers (for faders and rotaries), note numbers (for buttons) and channels (for each bank) sent from the MIDI banks via a software editor available on the KMI website. MIDI communication to and from the K-Mix's MIDI banks travels through the same USB port that carries audio but you can also purchase the KMI MIDI Expander if you need extra MIDI ports. This is connected via a second USB port on the K-Mix, which is labeled Control. There's a dedicated virtual USB port dedicated for receiving MIDI control for the Mix bank, separate from the virtual ports for the MIDI banks and the MIDI Expander. While this lends itself to a logical separation of duties, it may end up being somewhat confusing to some users and prevents the K-Mix from being used by USB host devices like the iConnectMIDI.
The software editor leads into my main gripe with the K-Mix as it's currently shipping—compatibility with non-OS X systems. Producers who use Windows will find neither an audio/MIDI driver nor a version of the software editor for their OS of choice. More troublingly, at the time of writing the K-Mix was also incompatible with the iOS, despite the manual stating otherwise. Reportedly, there is a firmware update coming to address this last point, but no dates have been provided by KMI for its release. If they can sort out the stereo linking and add compatibility with Windows and iOS, the K-Mix will be an essential purchase for any traveling musician who wants rugged portability combined with a versatile unit that can do three jobs at once. For a bus-powered unit I was impressed with the sound quality and loudness KMI achieved—it's safe to say I haven't used anything like it before. But if you don't currently have a Mac running OS X, you may be better off waiting to see what KMI does with the K-Mix in the near future.
Ease of use: 4.1
Build Quality: 4.7