Need help with Klipschorns/Electronics and mother.

I just realized how old this thread is....WOW😄

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.

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.

@daledeee1 How do you find 22 year old threads? Just curious!

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.  

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

I have hooked it up + to - and + to - for both channels and it definitely sounds better than having it hooked up + to + and - to - for both channels. I didn't think this should make a difference either, but it was very noticeable to all. Maybe we just improved a connection?

Without getting into all kinds of further permutations of ways to 'improve' this system, my advice FWIW is to go with plan B and give back Mom what she wants. It's your safest, simplest, and ultimately cheapest course of action given the situation, and nothing else you could try to do even with the best of intentions will probably result in more satisfaction on the part of the owners. It seems as if the sound they were used to was dependent upon utilizing the loudness contour and tone controls of the Crown full-time, and that the new amp presumably has more gain than the old amp, which didn't highlight the hiss from the old preamp so much. Quit while you're still within earshot of being ahead, and beat yourself a hasty - if wiser - retreat to the status quo.

As for the speaker hook-up polarity deal, to get the change you observed you need to have reversed only one speaker's leads, which would put the two speakers in-phase with each other if they had been out-of-phase before, resulting in stronger bass response, as well as correct stereo imaging. Changing both speakers' hookup polarities at the same time will reverse the absolute phase of both speakers together (something not audible for the purposes of this discussion), but would not affect the relative phase congruity between the two speakers. This all tranlates as, just make sure the two speakers are hooked up the same way as one another at both the amp and speaker ends (+ to + and - to - *or* + to - and - to + for *both* channels), or if you can't easily look behind the speakers, just go with your ears.