Hello Mike. Sorry for the late reply. Yes, that is indeed what my post says - it is possible to apply DSP to DSD without any conversion to PCM. There is only one software that can do this: Signalyst HQPlayer. https://www.signalyst.com/
The downside is that you need a rather powerful computer to do it. To give you an idea, I recently upgraded my HTPC to an i9-9600. This is enough juice for me to convolve 8 channels in DSD. My previous PC, an i7-6700, did not have enough computing power to do it. Unfortunately, I have now run into cooling problems with my i9. The Streacom case I am housing it in is unable to dissipate the heat despite being advertised as being able to do so! Now I will be building a new PC.