Shakti Stone

Go grab an old brick from the backyard (it must be a red brick!), clean it thoroughly, then paint it blue (you must paint it blue, and use at least three coats), and you’ve now got a great substitute for a Shakti Stone at a fraction of the price. The paint might set you back $10, but such a small price to pay for such an incredible improvement to the sound quality of your system. You can expect a lower noise floor, a wider and deeper soundstage, and more definition of the individual instruments. Go ahead and give it a try. You are likely to enjoy the exact result as described above.

@wesheadley Nope, won't work. One must pay

Ok I'll sell you a red brick for $175 and include shipping and PayPal fees

These work but you need a mid level or better high end audio system to hear the effects of what the metal does for electrical/magnetic fields. 
 

I have one under my pass amp where the toroidal transformer is. The amp

is on a raised stand. Moving the stone away from under the toroidal transformer the sound becomes a little less clear and some fine details are lost. 
 

Have tried this on my buddies entry level high end amp. Really could hear no difference on his audio system. 
 

if you have a well put together high end audio system in the $15k+ range the additional clarity the stone provides is noticeable.
 

This is a final tweak when one has already minimized other distortions from cables, isolation devices, etc.