Synergistic Research's Tranquility Base was introduced circa 2012. They demonstrated it at audio shows by placing under a digital device--computer, music server or dac--and turning on and off the power. You can read reviews of these demonstrations--virtually everyone heard an improvement in soundstage, presence and high frequency. I too heard these improvements but sad to say I no longer have the outlets to accommodate its power plug and grounding plug.
I pay PayPal fees and packing and shipping. Here's a review to whet your whistle:
The unit is in perfect condition with a few scuff marks on the polished surface--hence the 8 rating.