My older Wilson speakers have the Focal 1" inverted titanium-coated tweeters. They have a bad reputation for harsh highs. When I first got them, I concurred. Not anymore. Now, they sound sublime. Zero fatigue. The solution was cleaning up the AC power - with special attention to the digital components.
All of the above suggestions about the room, room treatments, speaker placement, speaker toe-in are correct - as is clean power. It takes a fair amount of tweaking to properly dial-in good SQ. The distance between the speakers is based on several factors. If they’re too far apart, the soundstage becomes defocused & delayered - a vocalist sounds like their mouth is 5 ft wide.
Here are assorted discussions.