So after spending nearly £400 on decent software I feel like I am getting nowhere at the moment. 
I am pc based running xp with the RME Digi96/8 Pad sound card running Wavelab 7.
So far I am able to send a signal out of the pc, through DAC, analog gear, back in to ADC then back in to the pc all fine. When I play around with the output on the mastering compressor I can see the level change on the screen but I hear no different through the monitoring.
I have tried to do a little research using the search button but didn’t find anything that helped, hence why I am posting up here.
Any help would be greatly appreciated.
Cheers. 