According to Rick, most benefit is having the MC-0.5 plugged into the receptacle, next is a power strip. Least effective is in an active power conditioner (YMMV).
I had one in a duplex and one in a power strip on the same line. I then changed the setup by plugging both into a T-adapter and got more of the 3D effect...
https://www.homedepot.com/p/GE-15-Amp-Grounded-T-shaped-Outlet-Tap-Adapter-Orange-50281/203716851
(I'm using 3 standard MC-0.5's)
I had one in a duplex and one in a power strip on the same line. I then changed the setup by plugging both into a T-adapter and got more of the 3D effect...
https://www.homedepot.com/p/GE-15-Amp-Grounded-T-shaped-Outlet-Tap-Adapter-Orange-50281/203716851
(I'm using 3 standard MC-0.5's)