If you are using asio drivers, know that asio has the unnerving trait of using the same device for both input and output, and since the guitar link has not audio out, you have no monitor... period.
There is a workaround. Asio4all.
By configuring asio4all properly, you can assign inputs to both the guitar link and the UCA, and outputs go to the UCA. What I'm not so sure about is output latency, but asio4all will allow you to adjust and compensate for that.