There was discussion in a post dated 5 September 2014 that is similar to mine. There was suggestion that Audacity might be enabled to accept more than single mono inputs from a pro devise like the RME UFX.
Apple’s Audio MIDI Setup acknowledges the RME UFX, but doesn’t let me access any of the inputs.
The RME works with other DAWs (REAPER, Studio One etc).
Is there something I’m missing OR is Audacity not yet able to link to RME, or is it an Apple issue?
Audacity is (still) only able to access one “device” at a time. The number of “audio channels” available to Audacity, depends on the number of audio channels that the “device” has.
Most common (generic) sound cards have drivers that provide “up to 2” recording channels, so in Audacity you can select either “1 channel (mono)” or “2 channels (stereo)” in the Device Toolbar (https://manual.audacityteam.org/man/device_toolbar.html)
Some 4 channel devices provide “up to 4” recording channels. In this case you will be able to select 1, 2, 3 or 4 recording channels in Audacity.
Unfortunately, some 4 channel hardware split their recording channels between two device drivers, so Audacity sees two “devices”, each capable of providing “up to 2” channels. In this case, Audacity can select only one of these devices at a time, and record from either channels 1 and 2, or channels 3 and 4. Fortunately, macOS provides a solution to this, which is that you can create an “aggregate device” which combines these two “devices” into a single “aggregate device”. By selecting the “aggregate device” as the recording input in Audacity, you then have access to all 4 channels.
At the end of the day, it all comes down to what the device drivers provide.