Need help with Klipschorns/Electronics and mother.

My parents' system consisted of Klipschorn speakers with a Dynaco ST-120 solid state amplifier and a Crown IC-150 preamplifier. This system sounded satisfactory to all concerned for about 20 years. Then one channel of the Dynaco died. Rather than having it fixed, I decided that they needed to upgrade to a Rotel RB980BX amplifier. The sound was immediately worse, but the most obvious problem was a hiss coming from the Crown preamp and amplified profusely through the Rotel/Klipschorn combination. I sent the Crown back to the manufacturer to be refurbished. They sent it back and said it was now perfect. The hiss persisted. I bought a Rotel RC980BX to replace it. The hiss is now gone, but the Rotel preamp has no "loudness" button, and no tone controls to tame down any harshness in the upper midrange/vocal area. The K-horns now sound shrill like they never have before, have no bass, and my Mom won't forgive me, PLEASE HELP! I am actually thinking about having the Dynaco fixed and putting the system back to its original configuration. My Mom would never spring for a good SET amp.

Footnote: Someone please explain why when I reversed the polarity of the speaker wires, the K-horns immediately sounded better (i.e., more full bass). In my estimation I have the speakers hooked up backwards, but they definitely sound better?????