Back in 2014, I bought an ARCAM rDAC, recently discontinued, seemingly new, said to be a refurb, on eBay for $314, including shipping.
It sounds great and it's hard to find a versatile DAC in this price range. At first I used the RCA S/PDIF coax input and it works great. The optical Toslink is fine.
It gave intermittent dropout from USB when I had the 2 meter USB cable stretched out horizontally to its full length, (like an antenna).
I added a ferrite bead to each end of the USB, but no joy. When I moved the laptop to the rack, the problem went away completely. I live in a townhouse with a lot of wifi traffic, which might have contributed. (My iPhone sees 9 other networks in my living room!)
Everything matters; but we all knew that.