The concert that Esa-Pekka Salonen conducted Saturday night at Walt Disney Concert Hall was enjoyable, in no small part, for what it didn’t have. There weren’t any familiar works on the program, a circumstance that has the tendency to keep a listener on his toes. There weren’t any masterpieces either, at least not of the certified variety, which was a sort of relief from the museum aura that so many programs have, where the listener sits in a pool of awe, admiring. No one talked about the music at concert time, explaining it and nudging our judgments. The only words that Salonen uttered were an introduction to a distinguished guest in the audience, Irina Shostakovich, the composer’s widow.

There is a kind of absence in Salonen’s conducting, too, that makes it enjoyable. He doesn’t put a lot of spin on the music, doesn’t grandstand with it, or milk it. One felt that the music was put first Saturday night, and Salonen stood out of the way. That is not to say he didn’t do anything, however. The performances maintained a remarkable energy throughout and, in the case of the second work on the program, a noticeably practiced hand was at work in the pacing. What’s more, the orchestra was in excellent fettle and played with that fine clarity of texture that Salonen has long been noted for.

The big news was the world premiere of “Orango,” an uncompleted opera by Shostakovich written in 1932, and only rediscovered in 2004. The composer finished the Prologue in piano/vocal score and Shostakovich scholar Gerard McBurney orchestrated it, basing his work on other Shostakovich works of the time and on the ballet “The Bolt,” two sections of which the composer reused here. The Prologue lasts around 40 minutes.

It’s excellent music, written when the composer was still in his 20s, brilliant, frenetic and whacky. A lot of it is music-hall parody, waltzes giddied up, pratfall cadences and the like. McBurney justifiably uses saxophones, a drum set, car horn, slide whistle and banjo in the score. There is a wild orchestral galop (I think) partway through that takes the breath away.

The plot concerns a half-ape, half-human hybrid named “Orango,” on display for the masses in the Prologue. There are singing workers, a host, and various personages involved in the story to come, the opera itself, which was apparently to be told in a flashback.

Peter Sellars directed, and he was up to his usual politicizing tricks. His modus operandi is to make things relevant to our times, as if we wouldn’t get the message otherwise. For the overture and then when the workers sing of the terrible jobs they had under the czar, a series of slides showing mass protests flashed on the screen above the orchestra, some from the Occupy Wall Street assemblies. Juxtaposed with those photos (often flashing quickly) were others of military hardware, explosions, and foreclosure signs, our evil government at work.

The singers were dressed in plain clothes, as is Sellars habit. Orango wore a T-shirt and jeans, and carried his own ladder to mount his own enclosure, a raised pen on stage right. The flashing photos distracted, but they did create their own rhythm, in tune with the hectic music. For a couple of ballet interludes, old black-and-white footage of dancing ballerinas was used charmingly. A journalist character hectored Salonen on the podium (wink, wink). The singing, all fairly rudimentary in the Prologue, was capable. Ryan McKinney made a lively tuxedoed host (The Entertainer) and Eugene Brancoveanu a suitably threatening Orango. The Los Angeles Master Chorale, or a portion of it, served duty as crowd and workers.

It was all entertaining and interesting. It is perhaps unfortunate that only this slice of the work survives, but then we have other similar works by Shostakovich from the period (including the opera “The Nose”; he had also begun “Lady Macbeth of the Mtsensk District” by this time) that will have to stand in.

The second half of the program was devoted to a rare performance of the Symphony No. 4 from 1936. Shostakovich withdrew it in the wake of Stalin’s threats over “Lady Macbeth” and the work was not performed until the 60s. What is not always mentioned is that Shostakovich withdrew the Fourth after 10 rehearsals and, disingenuously or not, professed never to be happy with it.

The Fourth is a mess, a glorious mess, certainly, but a mess all the same. In three movements and some 60 minutes long, it meanders through an endless series of complexities and jump-cuts, congealing but little. The orchestra is huge (the largest of any Shostakovich symphony), the harmony is dissonant and the explosions are enormous, but much of it is chamber music calisthenics. In fact, the entire thing is full of vitality, and that’s what carries the day; it’s just that the composer seems to have thrown too much in. Furthermore, his aim appears to be to discombobulate the listener rather than to show him the way, and at this he succeeds. The ending is a case in point. It leads up to colossal C-major chords in the brass as if triumphant, but ends muttering gibberish in C minor. One could say that this is an early sign of Shostakovich the Enigma, but it really just leaves you scratching your head.

The perhaps uncomfortable irony is that Shostakovich became a better composer once Stalin threatened his life. It focused his energies and turned his music towards his signature mode: Ambiguity.

Salonen and the orchestra gave it a potent and virtuoso performance, loudly appreciated by the audience.