1. Check the TX knob on the Signalink, it may be turned to a minimum and adjust to just tripping the ALC for a clean signal output
2. Check to see if the speaker output selected from the sound menu is USB CODEC
3. Check the volume out from the sound card, maybe the level's too low
Hope you got it working by the time you read this.
I did not have a chance to work on it last night. I ended up working a double and a half... 20 hours. I will probably look at it tomorrow now.