ABXTester is an application for testing whether two sounds are distinguishable. It is intended by the developer to allow the user to determine objectively whether compression or re-encoding has made an audible difference to a sound file. The user loads the original and modified versions, and the program randomly assigns one of the versions to five "X" values for playback. A quiz is then given on which "X" belongs to which version.
While this application works just fine and could theoretically be used for sensory or behavioral experiments, the interface is such that it would suit the needs of only the most informal procedures. Garish orange and green adorn the interface, and notification dialogues are barely comprehensible. The number of samples and number of tests is not adjustable in any way, although it is possible to re-randomize the test sounds.
Sam's Protip: Any lossy re-encoding of audio is going to cause a loss in audio quality. It should be pretty obvious whether that's a noticeable loss without having to run this experiment on yourself.