New system has fatiguing, harsh high frequency sounds. How to fix?


I just purchased my first audio and home theater system (other than a bluetooth speaker or computer speaker system). I use it for listening to music as well as watching movies. It is a tremendous upgrade and I’m enjoying it. It has clarity and detail that I have never heard before. However, I notice a harshness in the high frequency sounds when listening to music.

I would like my treble to be smooth, sweet, soft, silky and gentle. Right now it is the opposite of that. It is annoying, screechy, metallic and harsh.

I am seeking a solution to that issue. From the little I have been able to find on this subject, it seems that room acoustics might be a big part of my solution. Is that true? If not, what is my next step? An equalizer? I can’t see many options for big changes in speaker placement. At most I can move them a few inches or change the angles.

My listening room is about 11.5 feet by 11.5 feet and square except for the doorway in the back corner which protrudes into the room 18 inches x 44 inches. In the room are a bookcase, couch, end table, media center stand (holding TV, center speaker, receiver, disc player and Roku), computer & computer monitor, my speakers (and rear speaker stands), a ceiling fan and that’s about it... I’m describing the room on the assumption that the room (or its contents) are relevant to the treble problem I’m describing. (However, throwing some thick blankets over my TV and computer monitor, as a test, did not change the issue.)

Here are my home theater components:

  • Computer monitor: WASABI MANGO UHD400 40" 3840X2160
  • TV: LG OLED65C7P 65"
  • Receiver: Sony STRDN1080
  • Disc Player: LG UP875 4K BLU-RAY PLAYER BestBuy SKU 5979504
  • Streaming Box: Roku Ultra streaming player (model 4660)
I mention the monitors (and their size) in case they play a role in reflecting sounds.

Speakers:
  • Front 1: Polk Audio RTi A7 floorstanding speakers
  • Front 2: Polk Audio RTi A5 floorstanding speakers
  • Center Speaker: Klipsch RP-250C Center Channel Speaker
  • Subwoofer 1: Polk Audio PSW125 Subwoofer
  • Subwoofer 2: Klipsch R-112SW Subwoofer 
  • Rear/Surround: Polk Audio RTI A3
Speaker Layout: 5.1 layout with two pair of front speakers and two subwoofers.

The front speakers are on either side of the LG TV on the front wall (and near the room corners. The front speakers are angled in. Minimum distance to wall is 10", but measuring straight/parallel from back of speaker to wall is at least 18". From side of speaker to wall is at least a foot (one side of room has 30 inches). There is only 3" between each RTi A5 and RTi A7 speaker.

The rear speakers are behind the couch at each corner and against the back wall.

One subwoofer is in the back corner. The other is midway on the other wall and angled toward listening area.

For music, I usually prefer listening in 2-channel stereo. The dual pairs of front speakers are awesome. (I initially started out with a 7.1 layout but I prefer this layout now.) The high frequency problem exists even in 2-channel stereo. It also exists if I use only 1 pair of front speakers.

Wiring
All speakers are bi-wired, except the center (and subwoofers), which don’t support it. (Not bi-amp’d, just bi-wired*.)

Speaker wire: Mediabridge 12AWG 4-Conductor Speaker Wire (100 Feet, White) - 99.9% Oxygen Free Copper - ETL Listed & CL2 Rated for In-Wall Use

* https://www.qacoustics.co.uk/blog/2016/06/08/bi-wiring-speakers-exploration-benefits/

Banana Plugs:
  • Mediabridge Banana Plugs - Corrosion-Resistant 24K Gold-Plated Connectors - 12 Pair/24 Banana Plugs (Part# SPC-BP2-12 )
  • Sewell Silverback , 24k Gold Dual Screw Lock Speaker Connector
  • Ocelot Banana Plugs, 24k Gold Plated Connectors, Open Screw Type
BTW, my prior speakers were the Edifier e25 Luna Eclipse. I thought they sounded good and I did not remember them having these harsh high frequency sounds. After listening to my new system for a week, I went back to those for a test and they sounded horrible in comparison. The harsh high frequency sounds are much worse, and every other aspect is worse as well. (That shouldn’t be a surprise given the price ranges being compared, but my incorrect memory had been that they didn’t have this issue.)
lowoverdrive
You can run it on Rock.
Indian music is outside my American geographical music familiarity. So I’ll bow out of this discussion.

It's good you're going to separate your systems. If u just have to have a receiver, find one that has MOSFET transistors, instead of IC chips. Your sound will be much fuller and not as tinny sounding. There were many good suggestions about the room, contents and treatments. Glass is not conducive to good sound. It WILL take hours, for a new system to start sounding its best. Have a friend help set up your speakers. Inches and quarter of inches makes a huge difference. Try raising your speakers up a bit. Try one thing at a time, then add the things that worked together. Avoid square rooms. You can start with one, then do things to make the room rectangular.  Concentrate on a mosfet amp. You'll be amazed at the difference. 
@lowoverdrive

The one thing I have not seen addressed is what type media you are using? If you are streaming, what are you streaming? Mp3,? Flac? other lossless ? If you are streaming Mp3, there is much of your trouble. I only ask because I have been surprised at how many people know very little about bitrate and its influence on music.
artemus_5: I am generally not streaming MP3. I am playing CD's or lossless computer files (.wav or similar).
@lowoverdrive. I kinda figured you knew an Mp3 from Flac, wav, etc since you are running linux. I'd guess your problem is the HT receiver. They usually put all their marbles in the pursuit of video which calls mostly for a narrow range of midrange with powered Subs doing the explosions. I know Outlaw used to make a music friendly HT receiver. But its been a long time since I've heard anything about them 
You may do something like take the $1k you were willing to spend on acoustic treatments and spend it on a Tube integrated amp instead.
Here's an example. Not necessarily my 1st choice. Just an example. There are also some small one man companies which are producing very good tube  products for a small price  Also keep your eyes open for  PrimaLuna integrated which often come up for sale on the used market.
https://www.ebay.com/itm/Jolida-Fusion-1102-Integrated-Stereo-Tube-Amplifier-Silver-/122608274219?_t...