Given the contentious nature of audio commentary, especially on some audio discussion sites such as Audio Asylum, you might assume that any mention of LIAR would be in relation to someone's opinions, but that is not the case. LIAR is an acronym for Listening In Another Room.
And why would anybody purposely decide to listen to their stereo system from an adjacent room? Because it can tell you some things about your system and your room that you might not be able to discern from listening in the more usual location of your sweet spot.
The best software for a LIAR test is a solo instrument recorded in a dry, less reverberant space. I usually use a couple of my field recordings of Chris Thile on mandolin, and some solo piano pieces I've recorded over the years. If you only have commercial recordings, look for ones that feature a solo instrument or at most a trio. Masochists could use "The Sheffield Track Drum Record" which features a complete drum setup playing solo.
The goal in the LIAR test is simple - how close is the sound coming from your stereo to the sound of a real instrument playing in the next room? Some audiophiles and pro engineers will immediately dismiss the LIAR test because it is virtually impossible for any system to achieve a perfect score. That's true, but the point of the test isn't perfection, but to see how close (or far away) from reality a system can get.
Listening to a solo instrument from another room not only tells you how well you system is doing, but also gives you clues as to whether room interactions are coloring your system's sound. Is the room "singing along?" Is any part of the frequency spectrum overly enhanced or reduced? And finally, how "real" does your system sound?
For me the ultimate LIAR test occurred at a Chicago summer CES many years ago. I had just entered Reference Recordings/Spectral room when I heard the sound of a marching band. My first thought was, "Who's playing that hokey music?" But a nanosecond later I thought, "Damn, that sounds real." Reference Recordings Dr. Keith Johnson verbalized what I was thinking as we looked out the window and saw about 1/8th of a mile down Michigan Avenue a marching band was playing. There was no bass, no treble, only midrange coming through the double pane window, but we both knew almost instantly that the sound we were hearing was coming from real live instruments. How could we tell? It was definitely a right-brained, perhaps even reptilian-brained emotional reaction - we both just KNEW.
That was the most realistic LIAR test I've ever heard...