Pet Sounds, in its original 1966 monaural 13-song incarnation, ran for a little more than 36 minutes. Since then, as it’s worked its way up to, or near the top of, pretty much every “best albums ever” list, it’s been reissued and expanded so many times that even the most dedicated fan could lose track. Among those, the 1996 30th-anniversary edition brought it up to four discs—including the first-ever true stereo mix, a few dozen in-progress session segments and alternate versions—while the 2006 40th anniversary edition augmented the original album with a “making of” DVD and other ephemera. Now, as Pet Sounds turns 50, Capitol has gone to town once again, with a new four-discer that reprises both the mono and stereo mixes of the album, offers largely the same session recordings and alternate takes, then tosses in various live recordings of the album material spanning the ‘60s to the ‘90s, the so-called “Stack-O” vocals (instruments stripped out) and, finally, a Blu-ray disc containing the various mixes plus bonus material. That’s a whole lotta Pet Sounds, more than five hours’ worth, in fact. Much of it makes for fascinating listening if you’re an aficionado, and will probably bore or at least confuse those who are not. For the former group, to listen to Brian Wilson playing the studio and directing his musicians as he builds tracks like “Wouldn’t It Be Nice,” “God Only Knows,” “Caroline No” is to hear true genius at work. But here’s the thing: In the end, nothing matches the experience of hearing the original, 36-minute Pet Sounds, in glorious mono, from start to finish. As rewarding as it is to have all these treasures shared with us every which way, nothing more, in the end, is really needed.