DSP volume control and upsampling to DSD output

Hello again,
these Corona times trigger some projects that help to drone out the impact of the restrictions most of us are affected by. So here is a new project and as almost always it appears to hit a wall due to my lack of understanding of the inner workings of Roon and some gadgets.

Wanted to accomplish a full up-sampling to DSD at the Roon core level, push it via RAAT to a Roon bridge (older notebook) and then move it through USB to a Denon USB 300 DAC (can handle DSD128). All set up correctly, convolution filter in place, but in this setup there is no other way to control volume than through the DSP. With the DSP volume control engaged, the PCM to DSD conversion turns itself off and disappears from the DSP setting screen.
I assume running the DSP volume control and at the same time up-sampling to DSD is mutually exclusive. If not, please guide me to a solution.

TIA