"ABX is a method of comparing two choices of sensory stimuli to identify detectable differences between them. A subject is presented with two known samples (sample A, the first reference, and sample B, the second reference) followed by one unknown sample X that is randomly selected from either A or B. The subject is then required to identify X as either A or B. If X cannot be identified reliably with a low p-value in a predetermined number of trials, then the null hypothesis cannot be rejected and it cannot be proven that there is a perceptible difference between A and B."

There's Lossless and Lossy sample of each track. "CDDA" is pure Compact Disc Digital Audio in .wav format. "MP3" is same segment encoded as variable bit rate .mp3 using LAME v3.100 -V0, then decoded to .wav

Which sample is which? Test your might. Challenge your conceptions. Use your best (non-wireless) headphones. You will still lose ;-)