Troubleshooting rDAC- Julia spdif connection

Can users please outline a procedure for re-establishing a lost connection between an rDAC connected by spdif to a Juli@ sound card in a 64bit Windows 7 system using JRMC at the front end?
I'm spending hours re-establishing a lost connection.
On a similar note, is it okay to connect an rDAC through both USB and spdif as long as I'm using one connection at a time?