I think it would be of dubious value. Looking at the C7R, apart from USB, it's only got Toslink (forget it) and RCA coaxial (not ideal).
If you did want to still use a USB-S/PDIF converter, then maybe look at the other two cheaper ones from Bel Canto, or alternatives like the iFi iLink, Audiophileo, etc. There are tons of converters around nowadays.
An alternative strategy is to improve the quality of your USB source (what is it, btw?). I use the iFi iUSB and it makes a big improvement to sound quality from my Squeezebox Touch and Windows laptops' USB outputs.
If you did want to still use a USB-S/PDIF converter, then maybe look at the other two cheaper ones from Bel Canto, or alternatives like the iFi iLink, Audiophileo, etc. There are tons of converters around nowadays.
An alternative strategy is to improve the quality of your USB source (what is it, btw?). I use the iFi iUSB and it makes a big improvement to sound quality from my Squeezebox Touch and Windows laptops' USB outputs.