While the Mackie ProFX mixers can receive multiple USB channels from your DAW, only USB 1+2 are fed direct to the control room (ie. monitor and headphone outputs). The others will, like any other source, be fed to the main input channels and thus the main mix, from which your computer/DAW takes its stereo input.
I’m an experienced computer user, but have relatively little experience using Windows with a DAW. I had a configuration that was working well a year or so ago, but recently started using it again and now have a problem that has defeated me! I use a Windows 10 (version 22H2) computer with a Mackie ProFX6v3 USB mixer, with Reaper as my DAW. I have the latest Mackie driver installed and the latest Reaper version. The problem is that everything going to the Mackie over USB (on channels 3+4) is coming back on the computer input channels 1+2, whether it’s the metronome or playback of other tracks. Even general computer audio (also set to use ProFX channels 3+4) shows up as an input. Input on channels 1+2 is working as it should, but intermixed with the unwanted output signals. So far I have tried:
- Checking and double checking the driver settings and routing matrix;
- Uninstalling and reinstalling the latest Mackie driver, Reaper version, and installing all driver updates from Windows Update;
- Swapping the Mackie for a small Behringer mixer that uses completely different drivers (not ASIO); and
- Using Audacity instead of Reaper.
The issue persists through all of this, which leads me to believe that it is something within Windows. I’ve gone into the advanced sound settings and reset everything to the defaults. Curiously the ‘normal’ audio on the computer works fine: output to Mackie channels 3+4, and input from the webcam’s microphone. Can you suggest what on Earth might be going on?
SOS Forum post
SOS Technical Editor Hugh Robjohns replies: I’d recommend carefully reading the manual for the mixer again. I think that the monitoring outputs from your computer/DAW software need to be routed through the USB 1+2 outputs — these feed only the mixer’s control room outs and headphones, and not the mixer’s main stereo mix bus.
In contrast, the USB 3+4 outputs from the computer that you say you’re using appear on one of the mixer’s stereo channels, and that gets mixed with everything else, before appearing on the mixer’s stereo bus — which you’re then recording via the USB 1+2 inputs to the computer. In other words, while I understand the head‑scratching, it’s a DAW output configuration problem. Thankfully, it’s easily solved at no cost!