Don Richard:I am running three amplifiers, so I suppose I need three Shakti stones for my setup, right?

Only if you're not using Dark Field (tm) Cable Elevators to keep vibration and static fields away from your speaker cables.

Considering how many of the over-$100,000-per-pair speakers are of horn design, and sound really good, you'd think the primary drawback of horn speakers is their high price.
Pat on the Island
510 JubScalas + Paradigm PW-2100, powered by Yamaha MX-D1 x 2,
EQ'd by Electro-Voice Dx38, controlled by Yamaha RX-V750,
fed by Technics SL-1400MK2 & Yamaha DVD-S550
6.1 Surround: above plus 2 Heresy IIs & 2 Belles