Quick interrupt! If I’m not mistaken the tiny little bowls work for headphones, too. Bigger sound, more energy, more dynamics, subjectively louder, much better and more powerful bass. What the ding dong?! I just installed twenty copper tube caps, half were 1/2" diameter, the rest 1". Almost all were placed in upper corners of the main room and other rooms throughout the place, you know, just to see what would happen. Whoa!!
addendum: I use glue dots to stick the tiny bowls directly to the wall or ceiling surface. One foot out from the actual corner. One one or more of the three surfaces per corner. Use only Super Strength/ Ultra Thin Glue Dots brand.