I gave up on Zadig. Not only did not complete without errors on my machine without a lot of magic, but when it did it did not install a recent enough version of libusb. I don't know if it installs a recent version now or not. It wasn't installing a recent enough version to work on my computer six months ago when I tried it.
I would do this:
1. Go here:
libusbx - Browse /releases/1.0.17/binaries at SourceForge.net
2. Download the Win version (not the WinCE version)
3. Unarchive it to some temp directory
4. Navigate to the M32/dll directory
5. Copy the .dll and .lib file to the root folder of your SDR# install
6. Make sure you have the RTL-SDR / USB line uncommented -- the line should look like this:
<add key="RTL-SDR / USB" value="SDRSharp.RTLSDR.RtlSdrIO,SDRSharp.RTLSDR" />
7. Plug your dongle in
8. Fire up SDR#
9. Click on the pull-down menu between the Start / Config buttons
- choose RTL-SDR / USB
10. Set your output audio device to your speakers or something as a test
11. Cick Start and see if it works
If this doesn't work, you'll know it as soon as you select RTL-SDR / USB from the pull-down menu
Mike