Klipsch Forte ii too bright, or is it my room ?

"...or my 1970's Pioneer receiver..."

Yup.

Room and amplification.

Wow! You are all over the map on this one.

It may be one item, or a combination of several, that is causing the brightness.
 First, your speakers. Some Klipsch models, for some people, are bright sounding. I personally, would not do anything to modify the speaker, they were designed, and built a certain way. Try toeing them in, a little, at a time.
 Next, is a room issue, and this may be a biggie.It would be less troublesome, and cheaper, to relocate your speakers to another room. If you can not, or do not want to do this, then, it may be best, to look into "room treatments’, to deal with reflections from the glass and tile.
 If you don`t want to go the room acoustics route, try near-field listening.
 In my humble opinion, I don`t think changing your electronics will rectify the problem, unless, you have a better sounding room. If the room was better for sound, then the next step, would be, some tubed components in your system, or new speakers.

BS…I bet that 70s amp has been good since the 70s.
The Klipsch are attractive because they are bright. They sound detailed in shop, but after a short while you have a head ache.
The room just exacerbates it.

Get rid of them while you can.

russ69, would a mid-priced tube amp work, +/- $500 ? I could keep the Pioneer for looks.