Well, I don’t really have an obligation to follow your advice, or anyone else’s. After all, we’re talking about my master bedroom, not a studio, in which case, I’d probably have professional soundproofing done.
I don’t know about “fixing”. I just know that the two most important things in sound quality are the device amplifying the sound (amplifier, receiver, etc), and the speakers. If you have a '70s or early '80s Sansui with decent speakers, preferably with an equalizer, that will sound great no matter how bad the room is soundproofed. On the other hand, you can have the perfect room in theory for acoustics, with the best sound engineers in the world soundproofing it, and if you have a bad amplifier and speakers, they will still sound like crap.
In my case, I have a weird master bedroom that is as weird as it can be, with a ceiling in two sections angled as if it was a house, but because of the layout of the room, I can’t even center the listening area. To make matters worse, the window is in like its own area, protruding from the rest of the room. It’s as asymmetrical as it can be, and I’m sure that any soundproofing engineer would say “Dude, just get another house with a proper square or rectangular room and call me back.” Not only in its layout, but in the sense that there’s stuff in different places like my desk with my three 32" monitors, and NI S88 MKII MIDI keyboard, Mac Studio and PC, to the other side with bookshelves with vinyl records, some CDs, some Blu-rays, and several more things that make this room impossible to soundproof properly.
And yet, my Onkyo receiver with my Emotiva speakers sound far better than anything else I’ve heard when it comes to sound quality, both for music and movies. I’ve been to audiophile stores where they show you the systems in the thousands, and in some really good movie theaters. None of them come close to the sound quality I get when the movie or TV series has basic decent sound editing, from the best in 4K Blu-rays, down to CDs.
Of course this is only when editing the Dirac Live EQ curve to my preference, otherwise this Onkyo is another current mediocre receiver, like most of them, because good sound out of the box seems to have died along with Sansui back in the '80s.