Unfortunately the elephant in the room is the fact that there is no absolute standard for polarity through the recording/mixing/mastering chain. Some albums are released in "correct" polarity, many are not. But like Elizabeth says it really doesn't matter if it doesn't bother you. If it does, flip your invert polarity switch on your preamp or swap speaker cable ends (on one end only). I can tell a difference so that's what I do.
Phase Inversion, to flip polarity or not
I put a system up in another room using an older Bruce Moore Companion 2c Preamp with upgrades and a PS Audio HCA-2 amp with full blown Reference Audio Mods. The Bruce Moore just like the Audible Illusion recommends invert phase. I tried both ways and like both ways for different reasons. Without inverting phase it sounds fuller, drums sound bigger, horns have a little more meat on the bone. With invert phase there more detail, drum a little tighter but still has slam, maybe little more information, the PS Audio does help as it's pretty good at information retrieval. Anyone's insight or explanation to what I'm hearing please let me know. When dealing with a preamp recommending inverting phase which route do you go, just haven't decided which one is best, there both good.