sentences:  Thus the "difference" in sound quality between amplifiers is actually the ability of an amplifier to interface well with loudspeakers or a lucky combination of loudspeaker, amplifier, and room that works well together.The introduction of switching apparatus, with either metal connection (mechanical switches) or electronic processing (solid-state switches), may, some believe, obscure the differences between the two signal sources being tested.Skepticism advocate James Randi has offered a $1 million prize to subjectivists who can prove their most dubious claims through scientific blind testing.