ASIO4ALL does exactly what the Steinberg driver tried to do—but it works on Windows 11.

Problem: Mono inputs or missing channels. Fixes:

The ASIO (Audio Stream Input/Output) DirectX Full Duplex Driver is a specialized audio driver designed to facilitate low-latency, high-quality audio communication between your audio interface and Cubase. Developed by Steinberg, the creators of Cubase, this driver enables full-duplex audio transmission, allowing you to record and playback audio simultaneously.

If you specifically need the old driver for its multi-client capabilities, users have found that installing an older version (like Cubase Elements 6) and copying asiodxfd.dll from the C:\Program Files\Steinberg\Asio folder into your current Cubase directory can restore it.

His latest bright idea was a catastrophe. He had found a “legacy” DirectX Full Duplex driver buried in a Microsoft archive. The logic had seemed sound in his delirious state: DirectX handles low-level audio hardware access, Full Duplex means record and playback simultaneously—maybe it could trick Cubase into seeing the RME as a generic device. Maybe he could bypass the broken ASIO layer entirely.