Music under the stars is a long-standing summer tradition for orchestras. Different orchestras, of course, interpret it in different ways. At Tanglewood or Ravinia, you can hear the Boston and the Chicago symphony orchestras, respectively, play straight-ahead orchestral repertoire. At Wolf Trap, by contrast, the National Symphony Orchestra’s summertime series, NSO @ Wolf Trap, has evolved into a heavily pops-oriented array of sing-along movies and video-game extravaganzas. There’s only a small sprinkling of more “classical” programming, including the Tchaikovsky-Rachmaninoff evening the orchestra offered on Friday night.

The series does make a point of presenting at least one significant soloist every summer. On Friday it was the gifted young British pianist Benjamin Grosvenor, playing Rachmaninoff’s second concerto in his NSO debut. Grosvenor, 21, already made his local debut, courtesy of the Washington Performing Arts Society, in the spring of 2012, and he will be back next April. A solo recital is certainly a better way to appreciate his considerable gifts than Wolf Trap can provide; his playing seemed both sensitive and powerful, but thanks to the amplification system, he and the orchestra appeared to be inhabiting different worlds, particularly in the first movement.

Wolf Trap presents a lot of pop concerts, and its sound system appears to be built for that. It’s remarkable, in fact, that in this age of high-tech sophistication, sound amplification of live concerts, for classical music, at least, appears to be so crude. At last week’s “La Traviata,” the tenor’s body mike kept winking out; Friday’s concert not only separated the sound worlds of the piano and the orchestra but also cranked up the bass so much that the Tchaikovsky waltzes in the second half of the program (from “Sleeping Beauty,” “Serenade for Strings,” “Hamlet” and “The Nutcracker,” as well as the Allegro movement of the Sixth Symphony) sounded in places as if they were aspiring to rap.

I sat in the orchestra seats for the first half, the better to see the soloist and appreciate the NSO’s capable assistant conductor, Ankush Kumar Bahl, who was making his Wolf Trap debut as well. For the second half, I moved out to a blanket, for the sake of comparison, and found that little was lost in terms of sound and much was gained in terms of ambience. This kind of summertime concert is about conviviality, sharing a mood; the picnic basket, rather than the CD, has become the summer concert’s iconic souvenir. This isn’t the place to nitpick about how the NSO sounded, which was hard to determine through the amplification, in any case, or to do anything other than applaud Bahl’s ready banter with the audience, including a concise and informative precis of the 1812 Overture, which — of course! — ended the program.

Pianist Benjamin Grosvenor’s playing seemed sensitive and powerful, but he was undermined by Wolf Trap’s sound system. (Sussie Ahlburg)

Emil de Cou, the series music director, introduced the program by observing that the traditional cannons were being eliminated from the overture due to the sequester, to be replaced by drums. This turned out to be not only a joke but also misleading: The cannons were present, and very real, and very thunderous, and very exciting. It made me long for the time when the orchestra would have played unmiked so that the cannons were on the top end of a natural dynamic spectrum, rather than being juxtaposed with the rather anodyne wall of infinitely manipulable sound. Certainly they were exciting, and made, as they should, a rousing climax.

Assistant conductor Ankush Kumar Bahl led the orchestra in works by Rachmaninoff and Tchaikovsky. (Scott Suchman)