The La Jolla Music Society opened SummerFest, the 25th annual chamber music festival, at Sherwood Auditorium on Aug. 5. One of the most exciting and exuberant concerts in recent memory, it proceeded from the selection of music and the soloists, plus the remarkable cohesion of the Festival Orchestra, which comprises choice solo and first chair artists and a number of fine players ordinarily heard with San Diego Symphony, including bassoonist Valentin Martchev and his wife, flutist Pamela Vliek Martchev. One seldom thinks of the double bass as an articulate solo instrument. The programming of Giovanni Bottesini’s “Grand Duo Concertante” for violin and double bass convinced the listener otherwise, and it takes the prize, both for music selection and performance, by young violinist Augustin Hadelich and equally young virtuosic bassist DaXun Zhang. Performance of the richly textured and melodic piece, rife with wonderment, almost didn’t happen. The conductor’s score had not been deposited on SummerFest artistic director Cho-Liang Lin’s podium, and to his consternation the librarian could not be found. Suddenly, a man emerged from the wings, score in hand, and both the day and the evening’s hit selection were saved. Bottesini (1821-1889) was himself a bassist, and wrote quite a bit of music for his instrument, including concertos, duos, opera paraphrases and a series of 30 etudes. Recipient of an Avery Fisher Career Grant and the first bassist to win the Young Concert Artists International Auditions, the dazzling DaXun Zhang teaches double bass at the University of Texas, Austin. Hadelich, gold medal recipient at the 2006 International Violin Competition of Indianapolis, appears this season with the Los Angeles Philharmonic and The Cleveland Orchestra. The two appeared to be having a blast with each other and with Bottesini, and the audience responded with a vociferous standing ovation. The duo answered with an encore, Henri Wieniawski’s “Etude-Caprice in A Minor,” originally written for two violins. Almost as surprising musically, esteemed conductor/violinist Jaime Laredo and Lin performed Wolfgang Amadeus Mozart’s “Concertone for Two Violins in C Major, K. 190,” written when Mozart (1756-1891) was a lad of 17. During the opening allegro spiritoso, the oboe (Lara Wickes) and a cello (Trevor Handy) become conversational co-conspirators in this thoroughly delightful work. The third major selection of the opening concert was Mozart’s “Piano Concerto No. 25 in C Major, K. 503,” performed by acclaimed pianist Andreas Haefliger, who conducted from the piano, oddly sounding as if the composer were Beethoven. The soloist and Festival Orchestra quite filled Sherwood Auditorium. Haefliger was co-conspirator in Lin’s promised surprise, an appearance of the extraordinary violinist Gil Shaham to play a trio performance with Lin and Haefliger of Pablo Sarasate’s “Navarra for Two Violins and Piano.” SummerFest continues through August 27 at Sherwood Auditorium and St. James by the Sea. For programming details, visit www.ljms.org. Upcoming performaces: • Serenades and Romance Friday, Aug. 12 · 7:30 p.m. • Assad Brothers: Legends of the Guitar Sunday, Aug. 14 · 3 p.m. • Mozart II: The Sublime Spirit Tuesday, Aug. 16 · 7:30 p.m. • Commissions and Premières Friday, Aug. 19 · 7:30 p.m. • Tokyo String Quartet Sunday, Aug. 21 · 3 p.m. • Mozart III: Quintet Masterpieces Tuesday, Aug. 23 · 7:30 p.m. • SummerFest Finale Friday, Aug. 26 · 7:30 p.m.