I'm not certain about DSD 1.05, but every version of DSD I've used has opened a command prompt window on it's own. But if you're using vb cable to input the audio into DSD, you probably should start it from the command prompt as you need to specify the input device (your vb cable). If you open a command prompt and type dsdplus it should show a numbered list with your available input devices. Find the number that corresponds to the VB Cable you are using in SDR#, and then specify that input. For example, if your VB cable is listed as input device 2, you would type "dsdplus -i2". Does that make sense?
Once you know this, instead of typing it every time, you can make a .bat file that runs when you click on it that specifies the input.