If your power amp does not have volume control (and is just a fixed amp that will add a fixed dB to any given input) then we would not recommend using only the Nu Audio card as the pre-amp as it has a fixed output RCA design. You can still vary the volume using Windows Volume control, but it is easy to change that accidentally (and software can change it without any intervention from you as the user) and there would be no volume control on DSD tracks (ie, max volume all the time). If you are using the Nu Audio as a DAC to the RCAs line outs, you will then want to run that to a pre-amp before your power amp, or run it to an integrated amplifier (which combines a pre and power amp into one unit).