Brilliant Pebbles, a new tweak, cheaper than high end cables.

Lucky they fixed the problem with the  none linear response of glass bottles.

"The original glass bottles for Brilliant Pebbles have been replaced by clear zip lock bags, which have a more linear response than glass."

As far as I'm concerned, it's small chunks of amber all the way.  I sticky-tape them to everything.  Just be sure they're nice and clear.  Those pesky prehistoric insects have a distinctly deleterious effect on what is otherwise a massive improvement in timbral presentation.

If your listening room consisted of a pebble encrusted cave you'd be set.

I would say be careful drinking a few beers in the cave, standing up without thinking a taking a stalactite to the head.

Maybe the very best way to find out where crystals should be placed in a given room is to map out the 3 dimensional space of the room using a SPL meter and a test tone, a good test tone is 315 Hz but they are probably others, too. Wherever you find sound pressure peaks in the room, including reflection points and standing waves, etc. that exceed the average SPL in the room by more than 6 dB, bingo! That’s where one goes! Example, upper room corners. Before you know it, you’ve got yourself a Fortress of Solitude, dude.