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?????
That is certainly possible - the only way to find out is to switch back and see if anything changes.

The Rotel could be harsh.  It sure sounds like something is hooked up backwards.

Fixing the Dynaco is an option but most who fix these end up with new innards fixing some weak points in the design.  You would, in effect, give you a brand new amp.  You can call Will Vincent or Vacuum Tube Audio for info.  Prices are on VTA so you can browse.  Otherwise small tube amps are available.  

Oh they are at the bottom of a thread page.  I got all excited when I thought I could help and forgot how old it is.  Haha.

Buy your parents a mint condition/refurbed Hafler 220 as the power amp. It would be wonderful with the Khorns, and will smooth them out. To further smooth them out if so inclined, damp the horns with a Dynamat type material, as this will tame them further, but after the Hafler purchase. If they were happy with the Crown preamp, the Rotel will be fine. My best, MrD.