It should, as the these pieces are designed to take a "dirty" incoming signal, and send out a "clean" one. The "clean" signal it sends out goes to your gear *AND* back to the outlet/duplex, hence a "clean" duplex (theoretically a whole circuit). The effect will *not* be as strong on the duplex (or circuit), but you should get a little bump.Cheers!
Will line conditioner do anything for the other receptacle in a duplex?
Would it provide the same purported benefit as the Venom Defender, Furutech NCF Clear Line or Magnetic Wave Guide products?