Pc, I have three of the panels I provided the link to on my side walls at prime reflection points to two of my main listening positions in teh room.
My OHM speakers are fairly omnidirectional so one can listen with a coherhent soundstage and imaging from most anywhere. In that case one must chose what listening locations to treat for. Its more straightforward when applying in teh case of more directional speakers with a small well defined "sweet spot".
The panels pretty much work as advertised. In my case, I am walking a fine line for best sound by applying the third panel, but I have chosen to lean that way.
Bass in this room, on my basement level with thin carpet and padding on concrete foundation, is quite controlled and excellent. I have dabbled with the idea of trying bass traps just to see, but have not been compelled to actually do it to date.
