During the second weekend of La Jolla Music Society’s SummerFest, the program was “romantic,” and the romance emanated from composers not usually placed in that category. To be a bit more precise, Saturday and Sunday programs Aug. 8-9 were titled “20th Century Romantics” and “(Nearly) Forgotten Masterpieces.” Between the music heard and the performers that brought eight works to life, there was something for most anyone who got themselves there, despite the term “20th Century,” a phrase many lovers of concert hall classics dread. After all, nothing beautiful or romantic was written after 1870, right? Wrong. The first piece to be encountered Saturday evening, Anton Webern’s 1906 “Langsamer Satz (Slow Movement),” made one gasp at the composer’s ability to write something so beauteous as to fill listeners with silently screaming ecstasy, and at the musicians’ audacity in playing triple pianissimos that demanded the suspension of breath throughout Sherwood Auditorium. The youthful Jasper Quartet — violinists J Frievogel and Sae Niwa, violist Sam Quintal and cellist Rachel Henderson — proved worthy of their numerous awards and of the exalted position they hold as resident graduate string quartet at Yale School of Music. In startling contrast, the Jaspers showed off their personalities as well as musical acumen with more complex “sonorities” in Paul Hindemith’s screamingly funny 1925 Overture on “The Flying Dutchman” as performed by a Terrible Health Resort Band at 7:00 a.m. at the Village Fountain. As my companion pointed out, “You have to be good to play that bad.” Included in Saturday evening’s concert were performances of Samuel Barber’s 1956 “Summer Music,” Opus 31, and Leos Janacek’s luscious and amusing 1925 Concertino for Clarinet, Bassoon, Horn, Two Violins, Viola and Piano. Concertino performers were clarinetist John Bruce Yeh, bassoonist Valentine Martchev, French horn Richard Todd, violinists Cho-Liang Lin and So-Jin Kim, violist Quintal and radiant pianist Orli Shaham. Powerful and charismatic, violinist Sheryl Staples was concertmaster of Saturday’s performance of Max Bruch’s melodious Octet in B-flat Major (1920) with violinists Frievogel, Niwa and SoJin Kim, violists Paul Neubauer and Quintal and bassist Chris Hanulik. As a prelude to Sunday afternoon’s “(Nearly) Forgotten Masterpieces,” the Jaspers showcased their touted expertise with the dread 20th-century music in performance of Henri Dutilleux’ (b. 1916) 1977 “Ansi la Nuit.” Violist Quintal charmed those present at the 2 p.m. prelude with his explication of the work, which is the composer’s imitation of the sounds (and possible horrors) of the night. Then the quartet cleansed listeners’ palates with a performance of melodist Hugo Wolf’s “Italian Serenade.” Sunday’s “(Nearly) Forgotten Masterpieces” featured Antonin Dvorak’s melodic, folk music-flavored “Bagatelles” for Two Violins, Cello and Harmonium (violinists Lin and Kim, cellist Madeleine Kabat, and on harmonium, Liza Stepanova). The other two works were big guys, the first, Mikhail Glinka’s Grand Sextet in E-Flat Major for Two Violins, Viola, Cello, Bass and Piano. The work is very nearly a piano concerto in three movements (the brilliant Shaham did the honors). Her impressive collaborators included violinists Alexander Kerr and Kim, violist Neubauer, cellist Fred Sherry and bassist Hanulik. Written when the composer was only 28, the work causes one to ponder what would have happened had Glinka not abandoned chamber music for opera. The romantic La Jolla weekend concluded with Ernst von Dohnanyi’s Sextet in C Major, Opus 37. Not only operatic and symphonic, it is an extremely complex war of the worlds between the waltz and jazz — complex in that there are few moments when the assembled forces breathe and play as one and transcendent times when they do. Combatants and collaborators were heroic and included Staples, Neubauer, cellist Charles Curtis, Yeh, Richard Todd and the terrific pianist John Novacek. It was a truly revelatory weekend of glorious music making, for which artistic director Christopher Beach and music director Cho-Liang Lin are profoundly thanked. For SummerFest programming this week and next, go to www.lajollamusicsociety.org or call (858) 459-3728.