I recently spent some time digging into the M-Audio Transit, a classic USB audio interface that has long lacked proper support on modern macOS versions. The official driver was discontinued over 15 years ago, and like many others, mine has been sitting in a dusty box for the better part of a decade. I’m excited to share a working firmware loader that brings this device back to life on Apple Silicon.

The project involves a custom macOS firmware loader built using IOKit. To build this, I actually had to decompile the original driver and firmware loader to understand exactly how the device expects to be initialized. By reverse-engineering the device flow—guided by GHIDRA decompilation—I was able to successfully handle the DFU (Device Firmware Upgrade) process and trigger the necessary re-enumeration to make the device visible as a standard USB audio device.

This was a fun afternoon project that took about 2 hours to get working. It did require some deep diving into how USB device initialization works on macOS, specifically dealing with IOKit-specific control transfers and the nuances of DFU states.

Beyond the technical challenge, projects like this are a great way to reduce e-waste. It’s satisfying to take a perfectly good piece of hardware that has been abandoned by its manufacturer and make it useful again in a modern setup.

You can find the full source code, firmware extraction tools, and build instructions at https://github.com/iRonJ/MAudioTransitAppleSi.

If you have one of these old silver boxes sitting in a drawer, it’s finally time to plug it back in!