I have never felt the need of acoustic panels, except in reh place. Vast difference of concrete walls and ceiling, vs. "padded" with acoustic boards was so huge, and made it clear how much help for good sound this was. Mainly for the drums. Formerly everything being hard echo bouncing from everywhere, and then becoming vastly better.
As for home listening, I generally do not have any empty space anywhere, where any sort of acoustic panels could be placed, nor I have noticed any need for them.
Most of the time, when I hear people talk about one specific element, like what type of needle they have in turntable, what speakers they have, what format they prefer in terms of sound quality... It often seems quite odd discussion when very few of small things mean that much if rest is "whatever". Like seeing lately tons of photos of people listening harsh noise with little tape recorders with built in speakers. People listening vinyl on turntable with same needle for decades, and perhaps complaining sound of vinyl "these days".. Or placement of speakers, one somewhere below the sofa, other on top of book shelves.. hah.. It's all "been there, done that" -category for me. When the stereosystem itself is good enough, there is vast improvement, but I can't see myself starting to make "room treatment", sitting on armchair, surrounded by acoustic panels in perfect angle to speakers. I have always concluded, that I don't think artists who made it, or situation where band performed, requires such thing. It may be even counter productive.
For room treatment of home listening, my choice is more books, more records. No hard surfaces on sight, just cluttered stuff.
