Keith McMillen Instruments K-Mix Audio Interface, Control Surface & Programmable Mixer Now Available


Keith McMillen Instruments has announced that the K-MIX, a new Mac OS X-compatible audio interface and programmable mixer, is now available.

The K-Mix looks different than other mixers and it’s because KMI founder Keith McMillen wanted a mixer that was different than the mixers that were available. “I needed a very special mixer that did not exist,” explains McMillen, “a fully-programmable, MIDI-controlled, ultra-high-quality portable mixer.”

“Not having a mixer that could do all of this, when wanting to play live in a group without a sound man, was heartbreaking,” adds McMillen. “K-MIX had to be capable of tying all of my needs together — from live inputs to USB interfaces — to then operate as a fully-programmable stage mixer.”

The K-Mix is ‘not your grandma’s mixer’, according to KMI.  It has no moving parts, so it can be used as a portable mixer, without the fear of snapping off a fader or knob, while still giving you top audio quality, mixer functionality and control.

Here’s the official video intro:

The K-Mix features two ultra-accurate, low-noise µPre™ preamps, and a precision opto-tactile control surface that was designed from the ground up to command any DAW (Digital Audio Workstation), with eight channel faders, one master fader, four rotary controls, nine channel select buttons, four bank select buttons, and 17 function buttons.


The K-Mix also features flexible routing, per-channel DSP (Digital Signal Processing) — three-band, semi-parametric EQ, compressor/limiter, gate, master reverb (with individual sends per channel), and surround (Quadraphonic, 5.1, 7.1, and Octophonic) output — and can function without a computer.


Talking tech from an audio perspective, eight balanced analogue inputs on two XLR/TRS combo jacks and six 1/4-inch TRS connectors can comfortably handle signals up to +28dBu, while eight balanced analogue outputs on eight 1/4-inch TRS connectors are supplemented by one Micro-USB digital connection (providing audio I/O using 24-bit AKM convertors at 44.1, 48, 88.2, and 96kHz sample rates), MIDI I/O, and power. A second Mini-USB connection provides power and MIDI I/O (via an optional KMI Expander).

The low-noise µPre™ preamps proffer +48V phantom power, +60dB additional gain, unweighted THD of -107.6dBu @ 0dB gain, and a 96kHz frequency response of ± 0.56dB @ 20Hz–40kHz.


Meanwhile, MIDI position CC output on all faders, MIDI position CC output on all rotaries, and MIDI note output on all buttons brings MIDI control to almost anything.

Pricing and Availability

K-MIX carries an MSRP of US $599.99 and is available to purchase from any authorized Keith McMillen Instruments dealer or directly from the Keith McMillen Instruments site.  Technical details are also available at the KMI site.

39 thoughts on “Keith McMillen Instruments K-Mix Audio Interface, Control Surface & Programmable Mixer Now Available

  1. Seems like this is a great alternative for people who liked the idea of the Roland MX-1 but found the 4 channels, non compliant MIDI implementation, and Aira-only inputs too limiting.

    1. The MX-1 is a very different best – designed for ‘performance mixing’. I’d expect the K-Mix to be much better for people that are willing to dig into the technical details.

  2. awesomesauce. there really is nothing like it out there, finally a programmable mixer that i can toss in my gig bag without fear. not to mention a solid, clean studio board.
    heard they can be linked, might just order two. price point is decent too, ive owned the quneo and qunexus, both are indestructable. cant wait!

    as for the mac only, my understanding is thats just for the software, you can still use the full functionality if the mixer, just cannot edit the assignments. im sure a win version is coming soon from somewhere, if not official.

  3. I wonder if the mixer could work stand-alone so that I could also use FX sends from different inputs to different outputs. If so then this things seems like something close to the ideal choice for my needs.

    1. Interested in knowing this too. I would like to hook up a stereo guitar pedal or 2 to the ins/outs and use them as external send fx. That should leave me 4 ins for other gear. But can you use the outs like that (control send levels from individual tracks via the UI)?
      In any case this is the first KMI product I’ve been excited about.

      1. Lazyness.
        It says in the manual:
        3.5.2 – Aux Outputs
        Outputs 3–8 are K-Mix’s “auxiliary outputs”, or “aux outs”. These six outputs are split into three stereo pairs,
        Aux 1, Aux 2, and Aux 3.
        • Aux 1 = outputs 3–4
        • Aux 2 = outputs 5–6
        • Aux 3 = outputs 7–8
        Audio can be freely routed out any of these outputs using the aux send levels and aux panning.
        • Unlike the main output bus, the auxiliary outputs do not have any DSP effects.
        • The reverb send effect is not mixed in to the aux outputs.

        Though I’m not pretty sure I need stereo sends.

          1. Is it rude of me saying I was lazy not reading the manual at the 1st place?
            Anyway. If the converters are good then returning back to any of the 8 inputs should be fine.

            1. Yes. The synth world doesn’t need more grumps. Just move along if it annoys you. It’s depressing to see people bust out the ‘RTFM’ just to be rude. Synths are about openness, exploration, and wonder for a lot of us – and I would hope that the community would reflect that.

              1. It’s depressing to see people such as yourself judging people who admit they’ve been lazy not reading the manual. I was commenting on my own post, but you probably didn’t notice it.

        1. The manual notes you can address any individual aux out as a mono send by simply panning it hard. So you can have up to 6 mono sends. You just can’t allocate odd numbers of sends, even numbers/pairs only.

  4. I wonder if this is as indestructible as the QuNeo. When that came out, they made a video where they poured a beer on it, threw it out a two-story building, drove a car over it, and then hooked it up and it worked fine.

    I’ve got the same question as Justin, too, about the DSP effects. They really should have some audio or video examples that demo the effects.

    I’m not sure if this made it into the final product, but when I talked to the KMI guys last year, they said that the firmware of this would be user modifiable, and the hardware was expected to have extra CPU capacity, so you could potentially customize what this does and add additional features. The example he mentioned was that it could run a software synth.

    1. that was the qunexus. i wouldnt try that with the k mix 🙂 but its the standalone performance mixer i was looking for a long time. 8 in 8 out makes it also perfect for mixing and then sending it to daw.

    1. Does it make sense to keep making devices bigger than they need to be in order to support a legacy connector?

      Adding DIN MIDI jacks to the back of this would increase the size of this by about a third.

      What I’d like to see is the MIDI manufacturer’s organization get off it’s butt and standardize a modern, compact MIDI connector that can handle MIDI IN/Thru/Out. Then it would be easy for companies to make cables or adapters that had a small, modern MIDI connector on one end and the larger DIN MIDI connectors on the other.

      If they did that, you could have full MIDI connectivity on tiny devices like the Korg Volcas

  5. Reading through the manual and there’s a lot to love about this thing. Will ‘live comment’ bits that stand out and aren’t included in the article/video:

    * 8 page table of contents in the manual. Respect!
    * Inputs 1-2 can accept instrument level (‘low z’) inputs as well as line level inputs
    * Inputs 3-8 can accept phono inputs (RIAA preamps built in)
    * All I/O is via balanced connections
    * The outputs can be set up for ‘surround’ mixing.
    * The panners can work for stereo or a few different surround models
    * “The headphone jack can also function as its own discrete stereo output bus (9/10), or be used as a low frequency crossover output when mixing in surround.”
    * You can choose to monitor any input (pre fader) or any individual output bus via the headphones
    * iPad is supported (can’t power it though)
    * OSX from 10.6
    * “K-Mix will function as a MIDI device when connected to a Windows computer, but audio I/O
    functionality is not supported”
    * You can power it from either USB port
    * Sends can be pre/post fader. This can be set on the hardware.
    * ^ Same for the internal reverb send
    * Sends have a pan control per Aux pair. So you can get signal to any discreet output but looks like you can’t have, say 100% level to out 3 and 20% level to out 4—it’d be 80/20.
    * The main output bus has it’s own DSP strip (auxes do not)
    * Each channel has a sweepable HPF (aka low cut) but it can only be set via software. Cool that it’s sweepable, sad that it’s software only.
    * EQ is semi-parametric: sweepable high and low shelves plus a sweepable mid (with full Q). 18db cut/boost on each.
    * Reverb has a pre-delay and a max delay time of 5s
    * In addition to the 12 presets, there is a “reset” button to normalize the entire machine. Amen.
    * MIDI controller settings are _not_ saved in the preset. There are three banks for storing MIDI send settings and that’s it.
    * Shift + top of fader = solo. Shift+bottom=mute.
    * Faders can be grouped (groups set via software only)
    * USB Audio from the computer can either be mixed on the mixer (taking over the analog inputs to the channels) or simply summed and piped out the outputs (so you can have both at the same time)
    * an onboard 40hz-4000hz test tone generator is coming in the next version

    RE: MIDI (direct copy and paste from the manual):
    • When connected to a computer, MIDI can be sent from the computer to K-Mix for
    controlling nearly all of K-Mix’s audio parameters; this allows for fully automating your K-Mix!
    • When using K-Mix with the optional KMI MIDI Expander, MIDI coming into the Expander can also be used to control K-Mix’s audio parameters, allowing you to control K-Mix from external MIDI hardware.

    To me that sounds like cheap used Korg NanoKontrols will allow you to have fixed control over sends or pans or whatever. Plus fun stuff like LFO automation from a sequencer. Everything, including effects params, can be controlled via standard CC. Inputs 1-8 are MIDI chans 1-8, mains is channel 9 and the rest (auxes..) is channel 10.

    Signal Flow Diagram:

    Tech Specs

    I love it. I need more than 8 inputs and already have MIDI controllers as well as computer I/O. Otherwise, I’d be instasold.

  6. From all the info above, (and info at the website) it seems like it doesn’t have the option of being battery powered.

    Seems like a substantial over sight, knowing it’s designed to be so “portable”.

    1. It’s powered via USB, chances are that any battery capable of putting out ~500mA at 5V over a USB cable should work just fine for power.

    2. We found there are hundreds of low cost USB battery packs that could power the K-Mix for days. It did not make any sense to increase the size, weight and cost of the K-Mix when such a variety of quality solutions already existed.

  7. Hey everyone! Glad to see such a positive and engaging response to our announcement!

    I wanted to take a moment here to briefly address some of the open questions about the K-MIx.

    OS compatibility:
    K-Mix Audio Interface takes advantage of USB Audio Class 2.0, which is not supported by Windows at this time. MIDI control output is USB MIDI class compliant, which is supported by Windows. The K-Mix Editor (companion software) is Mac OS only at this time. Standalone operation is fully functional and not dependent on any operating system.

    More than one K-Mix unit can be plugged into a single computer to take advantage of a larger number of I/O over USB.

    Any input channel can be routed to any output channel for use as FX sends. Using the Aux sends and panners you can send signal to any discrete output. The output of the outboard effects units can be routed back into any input and used as a return channel.

    DSP Quality:
    We use top quality AKM converters for our A/D/A. Our DSP engine takes advantage of 32-bit floating point data for superb audio processing quality.

    Full Size MIDI Jacks:
    DIN MIDI compatibility can be achieved with the KMI expander.

    Thanks again for receiving the KMix with such enthusiasm! We at KMI are always down to hear what you all have to say, you can drop us a line at [email protected]

  8. I was hoping this would be a great alternative to the roland mx-1 also, if not can anybody recommend something in that vein?

  9. this seems like a good replacement for my zero8 when it goes….but….only 8 inputs? doesnt seem like enough 8 stereo inputs would be better

  10. Very interested in this but wish there was even more IO. I’ve been contemplating the Behringer XR series too but you need to jump up to the XR18 to get the USB audio interface. Maybe 2 KMix is what’s called for!

  11. This is exactly what I was waiting for to replace my aging, no longer supported Apogee FireWire Duet.
    Also since it can accomodate iPad as well, it will fit my current workflow beautifully.
    My wallet is ready… 🙂

  12. I’m seriously considering using the K-MIX as my main audio interface (like MOTU UltraliteMk3 or Focusrite 18i20). I am concerned however about any drawbacks I may be overlooking.
    If I understand correctly, I should be able to simultaneously record 8 tracks (24-bit, 96khz) in my DAW, while outputing the main channel on the K-mix main outputs and any other DAW outputs through the rest of the K-mix outputs? And also simultaneously control MIDI on the K-MIX (and/or use the expander as well).

    The manual on page 125 says: “When set to “Post”, it is possible to combine audio coming into the mixer from the analog inputs and from a computer (via USB) on the same output channel. The analog input audio and USB audio will sum together just before the output bus fader and mute.”
    So the described should function normally I guess?
    Thanks for the answer!

  13. I’ve had my wallet ready to go since this was announced. Literally been checking KMI website everyweek since Jan 2015 when it was announced. If this thing holds up to 3rd party review, it is precisely the soundcard/mixer for my needs. The feature set is so stacked I can’t believe the price point honestly. plus it’s USB powered?!! I mean does it actually get any better than this?
    I think i’m in the same boat as some of you already mentioned. I’ve had the apogee duet for years. hate the breakout cables, hated the one knob and having to do everything through their terrible software interface. Always wanted something like the Allen & Heath ZED range or the Presonus offerings, but the size of those units made them wildly impractical for my needs. This is the perfect answer for modern production workflow IMO. Solid small form factor, onboard DSP, USB powered, midi controllable, expandable. And the fact that it is coming from a company with a reputation like KMI, is the icing on the cake. Only thing stopping me from springing atm is They have never developed a product with audio circuitry. So I have to wait for the jury on that one. Hopefully there will be demo and review videos up soon.

  14. A list of neverending sub-menues, even mutes…MUTES! need two buttons press. This is not a “performance” mixer. Probably good for the studio but do we need such a compact mixer in studio?

  15. Mine arrived. One channel of the headphone output doesn’t work – it may be my fault, but I’ve done a bunch of stuff to check that I didn’t mess a setting up and it feels like it’s probably a hardware thing. Tried firmware updates and factory resets too, to no avail. I hope I can figure it out; nothing quite as frustrating as receiving some long-awaited thing only for it to break when you try to use it!

  16. Is there anyone who can compare the K-Mix preamps to the ones of Apogee or Focusrite? I would love to buy a K-Mix but have not jet found any review that talks about the quality of the preamps. Not even the Sound on Sound review!

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