Have you treated your listening space?

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That's the really funny thing.
Room treatment costs less than a couple of cable upgrades!
I got some pretty expensive draperies (my wife likes them too), some bass traps and 2" and 4" wall panels that look ok for under two thousand dollars. How much have you spent recently on component upgrades? I bet plenty!
It's just a matter of education, it's not that complicated in its basics.
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I tried a host of room treatments and achieved the best sound when I sold most of the stuff and used things like tall ficus trees, carpet, book shelves, proper speaker placement, etc...

I now have great sound and a great looking room.

look at my system pics.

my high dollar stereo would sound mid fi (and did) until i added the ASC traps and bass panels (DIY). diffusors on front wall helped as well.

IME, in a small - mid size room, they're a requirement.

the 2 most neglected factors in audio are room treatments & power conditioning. money spent here will yield bigger returns than in upgrading electronics.

I've treated rooms I've used for home recording studios for years, and worked in pro studios ad nauseum. That said, I'm firmly in the "no treatment needed in the hifi room" group...I like the ambient sound of a "living space" room, and find all I need to do is own normal furniture and move speakers around a little. My system sounds great, has standing waves here and there but not in my listening spot, and the bass is tuned by careful listening to a REL sub. When I record stuff and put it on in the "untreated" space, I hear it differently and that's a good thing.

Room treatments are not in the signal path so how can they possibly have any effect on the sound?

:-)