Help. System sounds thin and bright or harsh

My first thoughts all centered around positioning. But it sounds like you have covered that. Secondly floor and wall treatments. It would be really helpful to us if you could upload photos of your system and venue to virtual systems under your UserID. Often, one look can completely redirect the discussion to some relavent factor. 

I have owned lots of Pass gear and the line that sounds more in line with your interests would be the XA line. They are much warmer and more natural. Tubes… everywhere and anywhere are appropriate.

Parasound preamps are not known to be particularly trebly or hot on the top… but a good tube preamp will definitely more to your liking… maybe used Audio Reseach or Conrad Johnson… Rouge can be a bit hot for tube gear.

"Harsh" can be a result of out of spec distortion in any of the front end components. To rule that out you'll have to swap out each piece one at a time. If it solves the problem, then the offending piece can be sent for testing/service.

in your old room was your back up against a wall and now you are sitting out in the room?  

sitting up against a wall reinforces bass quite a bit.  

is the new room more lively / less furnished / less treated with drapes and carpet?  

also settings can change when gear is moved around.  could you be using the inverted polarity outputs on your preamp or one of them?  

Apart from a pair of REL T5x, I'd look at the tubes. Any idea what 6SN7s are fitted?  RCA VT231 or Ken-Rad 6SN7 are on the warmer side.

Thanks guys much to think about

Room is 13'2" wide in a loft with side walls extending 11 feet back from the front wall where the speakers are close to. Behind the seating position about 8 feet from the speaker plane is wide open in a loft of a two story home. Ceilings is vaulted 10 to 11 feet high as it is angled. Carpet is pretty thick. No room treatments as of yet.

But as Avanti1960 speculated I USED to sit against the rear wall in the old listening room and still didn't have the warm, full sound. Bass shy for sure. Now its wide open behind me except for a four foot high wall behind the couch or seat.

As for output tubes, I have two sets aside from the stock harmonix something or others. One pair is a set of matched Tungsol 6SN7's from upscale audio. The much better set is from RCA circa 1940's 6SN7 GT's.  Much more sparkle and "life" compared to the Tungsols. Tungsols help a tiny bit with edgyness but rob the sound. They can't compare to the NOS RCA's. 

Still playing with speaker placement but since I mentioned that this problem has followed me from listening room to listening room it leads me to think the problem is component related?? Maybe bad synergy. Maybe speakers really aren't up to the task for high volume but still sound thin at low volume  Call me crazy but even with all this the system has never sounded better, so I am re-invigorated to pin this issue down and upgrade if need be.  Its nice cranking the volume without disturbing neighbors.