The most elegant solution for modern macOS versions is an open‑source driver project hosted on SourceForge and GitHub. Officially titled “M‑Audio MIDISPORT USB 64‑bit MIDI device driver for MacOS v10.14+,” this driver was reverse‑engineered from M‑Audio’s original binary code and re‑compiled to support 64‑bit architectures.

You need to locate the (or the specific legacy driver for your exact OS version).

The USB port on a modern Mac will not power the Radium correctly without the handshake from the official driver.

Since no official driver exists for modern macOS, the following methods can restore knob/slider functionality:

If you are holding onto an older Mac to run 32-bit plugins or legacy software, you are in luck. The Radium 49 can run perfectly here.

If your Mac doesn't recognize the keyboard, try these solutions in order: 1. Power Issues (Most Common) Go to product viewer dialog for this item.

The official M-Audio Radium 49 drivers released in the mid-2000s were . Apple began phasing out 32-bit support in macOS Catalina (10.15) and eliminated it entirely. No 32-bit driver or software will run on macOS Catalina, Big Sur, Monterey, Ventura, Sonoma, or Sequoia.

The Radium 49 includes a standard MIDI output jack (5‑pin DIN) in addition to its USB connector. The keyboard can send and receive MIDI data through this traditional interface independently of the USB connection.

: Plug the other end into the MIDI IN port of your USB-MIDI interface or audio interface.

The project is also maintained on GitHub under the repository leighsmith/midisport-macos . The issue tracker there contains valuable discussions about troubleshooting, including cases where the driver appears to install but does not show up in Audio MIDI Setup. This is often resolved by ensuring that the old MidisportLoader startup item has been completely purged from the system.

This driver works with the entire MIDISPORT family as well as the Radium 49 and 61 keyboards, the Oxygen 8 (v1), and the Keystation 49/61. The same underlying USB protocol is shared across these legacy M‑Audio devices, so the driver effectively acts as a universal solution for many once‑orphaned pieces of gear.

I can give you a step-by-step connection plan based on your current gear. Share public link