Before you switch out your pre-amp, try a Musical Fidelity tube buffer stage X-10v3 between the CD player and the Pre-amp. This will eliminate "loading" while allowing maximum transfer between the two components. I recently purchased one and am extremely pleased with the results. You can purchase from Underwood HiFi for 375.00 shipped and return if not satisfied. I believe the X-10v3 will allow more dynamic contrasts in your system AND help give you some of that tube sound you crave.
John
John