Best method for PC to vintage pre-amp

Hi everyone. New member and novice here – I'm in the process of setting up a second system based on a Radford HD250. Will be using a turntable with it, but I'm looking for advice for the best low-budget method of getting digital music, from either my desktop PC or a usb stick to the Radford. I assume I'll need a DAC, but that's the extent of my knowledge.
Thanks for any help...