If I understand right, you want to output to two seperate devices: TV via SPDIF out, and desktop speakers via analog. You do not want to have to manually swap outputs.
Unfortnuatly, you don't have any other options. Windows can only output to once device at any given time; there are a few ways around this, but none that apply in your case. Your only option is to manually swap the output depending on the device you wan tot use. Adding another sound device will not help, as only one can be active at any one time.