Hi Zojokkeli,
According to Schiit:
USB Powered, No Drivers
Modi plugs into virtually any computer—Windows, Mac, and some of the most popular Linux distros, as well as iPhones and iPads—and requires no drivers to deliver great sound, up to 24/96 sampling rates. It features asynchronous transfer with individual crystal oscillators for the 44.1 and 48k sampling rates, and uses the USB Audio 1.0 standard over USB 2.0, and is powered by the USB port.
So no you shouldn't need any drivers for the Modi. Have you tried different USB ports, prefererably a USB port that is directly on your PC's Motherboard (not a USB hub)? It is also recommended to use a USB 2.0 cable 3 Meters or less.
Have you went into the Windows Control Panel - > Sound -> and made sure that the Modi was set as your default audio device?
Make sure to do the above step, and after you click on sound select the "Playback" tab. With the Modi connected via USB, under the playback tab it should show up as a playback device. Make sure you select it, then right-click on it and select "Set as Default Device"
Hope this fixes your issue. If not, please report back.