My "stereo" room has only three walls that open to a kitchen as well as the hall to the rest of the house. My house has a lot of hard surfaces, so the echo is like a racquet ball court. It is too severe for just using a rug and furnishings. My naive first step was a primacoustic panel kit as suggested by the company. It was not nearly enough to even notice a difference. Another issue was my speakers at the time (JBL 4367) had limited bass within that room. Upon measuring with REW, there is no good way to implement full range speakers in my room with even bass. I purchased a pair of REL s510s, but struggled to situate them using the instruction booklet.
Around 2021, I found Nyal of Acoustic Frontiers in San Fransisco. Using phone, email and google drive, Nyal directed me on a number of acoustic measurements. I first had to make a blueprint of the listening room and kitchen, along with providing photographs. He helped me optimize the position of the subwoofers, but that model proved too small for my speakers and too limited in adjustment. I was able to flatten the bass up to 60Hz, but getting rid of a large 60Hz resonance was not possible. I purchased JL audio f113s and their CR1, which fixed the bass.
For the second step, Nyal proposed a package of panels as well as their mounting locations. This included ceiling panels and six panels on a kitchen wall. I was put off by adding anything to the kitchen, but actually it worked out. They are vicoustic VMT panels, which blend in well. I also picked out the cloth for absorption and diffusing/bass trap panels for the wall. The cloth matches the paint. It is a nice geometric design. Visitors actually compliment it, but I am sure they think I am weird. I installed them all myself, which was quite a job. I will say a laser-level is a must-have luxury for this process.
The room sounded much better, of course. There was no change in tonal balance, really just a large decrease in reverberation time. There was a remaining issue with a resonance in the upper midrange I could not cure. It was a like gong go off on certain notes. I could decrease it with positioning, cabling, electronics etc., but it was always there. So I sold the 4367s. They are great speakers but they weren't for my setup. I was frustrated and wanted to move on to something easier, less ambitious. I will say the most underrated aspect of those speakers are the woofers. The bass is so articulate.
I moved on to TAD ME1, which I bought used. They are a little dry in the HF, but very pleasant sound speakers. They are more challenging to integrate in to my room as the bass rolls off earlier than I had anticipated. First I re-setup the subs in mono with DARO. I had move the TADs as well as the listening distance from the front wall many times before finding a position of both at the same time where the bass would fill in between 50- 150Hz. I also tweaked the damping and xover frequency on the CR1 to juice up that range as well. Then I used a laser measurement to mirror the distance between the two speakers and the listening position. That whole setup took about nine hours, which way less than number of hours I had already put in...hundreds of measurements. The sound is so pretty and relaxing, now. I do miss the 4367 woofers, though. The E1 and CE1 would better speakers for me, but I do not care enough to spend the money. I have other things going on in my life right now.
I highly recommend Acoustic Frontiers. There is a lot of value for those of use with room challenges, in my opinion. Nyal is very thoughtful and professional. Understanding room acoustic basics is not hard but an acoustic plan is complex.