ABX company has created hardware which allows an individual to test if they can distinguish any difference between two pieces of equipment, or other variables. The hardware randomly switches between the two alternatives, and neither the person running the test, nor the listener (they can both be the same person) know which alternative is active. This is a classic "double blind" test design to eliminate bias. Arny Kruger has posted free downloadable software to run tests yourself between two .wav files.

An ABX test is a method of comparing two digital audio files to determine if any audible differences between the files can be found.