Help. System sounds thin and bright or harsh

Do this just for grins to see if it’s a room treatment issue. Drag some mattresses from adjacent rooms into that room and place them against the wall and see if that makes a difference. I’m not suggesting this as a cure but to determine if it’s the room itself that is the issue. It may or may not be a big factor in what we’re talking about.

Andrew Jones tells a story about doing this at an audio show where they were stuck in hotel rooms that had terrible acoustics to do their demos. He said that they were voted the best sounding room in the show. They just asked room service for extra mattresses and placed them around, experimented and their end result apparently was quite amazing.

Not a permanent fix in any way but will certainly tell you something important.

I fully intend to use room treatments. already using cloth at first reflection points on side walls.  Used dedicated treatments before to try and tame Harbeth slh5's with boomy bass in my old listening room.  (ended up way overdamped, got rid of all the devices to start over) I feel that I should be able to get to a decent basis point with the overall sound before buying pricey treatment options that, in my mind, should be a means of fine tuning the sound.(keep it minimal) It was my experience that room treatments did NOT have instant or dramatic impact on the overall sound. This new room could prove totally different on that score, who knows.

Meantime, think I need to try a different pre-amp and send the JC2 out for a check up and possible service. Modwright/Oppo balanced outs straight into Pass Labs X250.5 amp sounds smoother than before but not robust enough, hitting variable volume levels in the upper 50's to mid 60's out of 100 and there's too much missing.

There's been lots of talk about using a pair of subs with the 30.1's. I am open to the idea but wonder since the room is wide open behind the listening position that I might get away with 40.2's and avoid trying to sync subs.  (did not like my SLH5's) Common sense tells me that's not likely.  Loft is 13' 2" wide with side walls extending 11 feet before opening up to a very distant upstairs back wall. I sit about 9 feet back from the front wall or where the speakers are. Ceiling is vaulted 10 to 11 feet high.  I feel the big Harbeths would be too weighty in that set up but certainly would warm things up. One can dream.   

re room treatments: unless you are in a glass bubble, your system should have the tone and characteristics (such as warmth) you expect without room treatment. 

Sell the Harbeths. There is nothing wrong with your upstream gear, the problem is the Harbeths sound like studio monitors. Studio monitors are not “warm.” 

@cymivka i don’t think adding subs are the answer to this problem. Sound like you may have a connection problem or an amp problem. But “ harsh” and “bright” aren’t fixed by subs. You’ll get harsh and bright with a lot of bass. My opinion.