@panzerwagon, a good post. I agree.
@noir59, "Treat the room only when all else fails" The room itself creates huge problems which happens in all rooms, an unavoidable fact and is the downfall of many potentially great systems.
If you have something handy like a bluetooth portable speaker for example a JBL Flip 3 or 4 or ? carry it into your tiled bathroom and listen then carry it outside and listen. The different sound is caused by room acoustics. Also place it on a table near the middle of your listening room, then try it in a corner on the floor and you will hear lots more bass. It’s not good bass it’s just more but boomy.
This simple experiment will help you understand how acoustics play such an important role.
Room treatment is paramount! Ignore at your peril 😲