I use the TunePak below....for going on 25 years now! Simple.
13x12x9 size Room....make it sound bigger.
No B.S., Micheal Green did start this for the home audio enthusiast.
I remember in 1994, ....people, even audiophiles thought I was nuts, until they understood and heard it. ....then the rest was history. The trick is...you don't want to end up with an anechoic chamber/dead. ...the room still needs some snap! I think a lot of people were helped/enlightened, by Robert Harley's first book (94, or 1995) on covering the basic's in your room.....even using a mirror. Now, get out the Laser, I suppose!
I currently just have the 4 upper CornerTunes deployed from MGAudio. For my lower corner's/bass traps and walls I found some one inch air conditioning filters to be effective. Poor man's like I said.
She ain't pretty...but in a dedicated room I don't care. The sound from my Decware gear that is pretty....forgettabout it. I did treat my ceiling too, at one time. My Adagio Tweeter's don't need it + the angling degree down of the top woofer...minimizes ceiling reflections.
https://www.michaelgreenaudio.net/roomtuneRoomTune TunePak
Every room is different acoustically and RoomTune for the last 25 + years has made the audiophile basic tune-up as cookie cutter and affordable as it gets. The RoomTune TunePak (as seen to the left) is a 10 piece set, treating 4 upper corners (CornerTunes), 2 midseams (EchoTunes) and 4 main corners (XLTs).
Off this desktop....and back to my Listening Room! I will grab my iPadII.
......enjoying my NOS Tungsram 6922 input tubes today with my Gold Lion Cryo KT88's. THE NOS Telefunken's for inverter's.
The first thing I do...when I walk into a Room that is supposedly set up for music.....is CLAP ECHO TEST.