Dear Yul1375,
You might want to concider a Space Tech Lab DA-64XT Super DAC. It has a Vacuum Tube Output Stage with a Vacuum Tube Rectifier. It also Up-samples your CD's. The Balanced Digital Input and Balanced Analog Out sounds the best on this DAC. Albert, of Space Tech Lab, knows how to design Balanced Circuits. You can also later up-grade with one of Alberts STR-104 Vacuum Tube Rectifiers that will plug into the DAC. This combination gives me one hell of a Soundstage with lots of air, and it still gives you plenty of Dynamics. If your Resolution Audio CD55 doesn't have a Balanced Digital Output, Albert could install one. Even if it does, Alberts Balanced Digital Output Stage sounds better. You could also go Digital Co-axial if you want, and still use the Balanced Analog Output on this DAC. You would have to order the DAC with Balanced Inputs and Outputs. Space Tech Lab Equipment is more than reasonable for the cost, Albert builds his own and can modify his equipment to better match your existing System. Just need to look up Space Tech Lab in Vancouver, Canada on the internet.