Check that your Windows sound level is not muted or at zero or something, shift slider to 100% for example...well that's super obvious, but why not list it!
I'd also check in Device Manager that you can see your DAC there and that there are no yellow exclamation marks showing equipment that is not installed properly.
You also need to power the E30 using the dedicated power USB cable (barrel power connector), you can't just run it from one USB port (the USB input for music doesn't power the device at all, is my understanding).
I'd also try uninstalling the Topping drivers, restart the PC, and test with just the Windows drivers....windows will automatically install the correct drivers on startup. If that doesn't work, then I'd have another go with installing the Topping drivers.
Oh yeah, and if your DAC is in pre amp mode then make sure you're at 0.00dB, which is max volume - just to rule out it being accidentally set at minimum volume or something.