TX Audio Source when using CAT PTT with Maestro C

I'm using my 6600 remotely together with a Maestro C.

My understanding is that when PTT is activated via CAT, the radio uses DAX as the transmit audio source, and the microphone input on the Maestro is not passed to the radio. Is that correct, and is there any setting that changes this behavior?

The reason I'm asking is that I process my microphone audio locally. I also run my voice keyer audio through the same processing chain, so that both microphone and voice keyer produce identical on-air audio (the WAV files themselves contain only raw, unprocessed audio). This worked very well with my legacy radio setup.

With my new Flex setup, however, I get no transmitted audio when running the voice keyer from N1MM — unless I press the PTT connected to the Maestro. In that case, the voice keyer audio is transmitted as expected.
I'm feeding the processed audio to to microphone input on my Maestro.

Of course, I could record my voice keyer WAV files with processing applied and route them via DAX (as intended). However, that would remove some of the flexibility of live adjustments: any change to microphone EQ or compression would require recording a new set of WAV files to keep the audio consistent.

Before reworking my audio chain, I wanted to check whether there is a setting that would allow me to keep my current setup. Otherwise, reverting to the DAX approach is probably the simplest solution.