You need to take the USB directly from the RPI. The Digi+ only provides a coax interface for the RPI. It's worth spending a bit on a decent USB cable because, as I discovered, they do make a difference, and eventually a reclocker if your budget will stretch that far. There are several threads on TAS on USB cables and reclockers.
Sent from my SM-G975F using Tapatalk
Cheers
Alastair
RPI4/PI2AES running PiCorePlayer/LMS-> AQ Carbon AES -> Topping D90 DAC-> Khozomo Passive Pre-Amp -> 4x Temple Audio Monoblocks powered by 2xLiFePO batteries->Van Damme Black Bi-Wired to B&W 804 Nautilus and Sommer Carbokab 225 Interconnects