Here is what I do to convert DSD to PCM. It is not straightforward.
In the Convert File options, I enable DSP Studio and in Output Format put some number in the > 768K line. For 1x and 2x DSD it does not really matter what you put there, as MC always converts to 1/8th of the original frequency - a 2.82 KHz DSD (1x) goes to to 352 KHx PCM and a 5.5 KHz DSD (2x) goes to 705 KHz. If you want, for example, a 176 KHz final output, you need to put 176 Khz in the 352 or 705 KHz line. Never done it, but I guess if you do 4X DSD it converts to 1410 KHz, and then the number you put in the >768 KHz probably is used to convert to a lower sample rate, like 176 KHz or 352 KHz.
Note that the DSP Studio option is the one you see in the Convert Format box, not the one in the general Audio options or in the Audio Path option. The options look the same, but the general options are not applied to conversion or vice versa. You need to set specific DSP options in the Convert Fomat pop-up under Options.
The code that MC uses for converting from DSD to PCM is a commonly available one that only converts to PCM at 1/8th of the original sample rate. If the final goal is less than the 1/8th sample rate, it is probably good to have the new Sox converter option on. At least, I presume that the second conversion uses Sox if the Sox option is checked.
As far as I know, the Sox DSD to PCM converter was not implemented.
Give that a try.