Rotel 1090, Bryston BP-25 or Krell KRC-3 pre-amp?

The Bryston is perfect. Any harshness you hear will come from something else. If there is something in your system that you are trying to counteract, however, neither the Bryston, nor either of the other two preamps you mention, will do that. Some tube preamps might, like an old AI M2d, but not the M3 or M3a, maybe a Melos if you can find one, and some of the CJ's. I'd figure out where the harshness is coming from first and get rid of that.

All the Pre's you mentioned are SS which may not accomplish your goal.

A tube Pre may be the best choice for you, tubes can absolutely take an edge off the highs. I found EI 12ax7 tubes to be very laid back. Pre's using 12ax7s or 5751s give a lot of choice. I am sure you will find some tubes that suit your taste well. A SS Pre will not have this "tweakability."

I like preamps which dont modify the sound at all. Which is probably why I liked the Bryston products so much. Having said that, I would recommend strongly that you audition, in home if you can, several selections before buying.

You may also be able to take some of that harshness out with IC selection. I thought that Cardas was a little laid back. Just a thought.

the bryston is natural sounding,,,,no edge at all.

None of those! Try a tube unit like a CJ or Audible Illusions.