For just a few months, violist Jose Flores and three pals from the UA music program, most of them graduate students, came together as the Sonora String Quartet. Despite all the tensions and technical and logistical problems involved with quartet playing, this ensemble purred along from the very beginning. Not that they took the musical challenges for granted; they worked hard on things like Beethoven's Op. 95 and Shostakovich's Quartet No. 8, and traveled around town with some of the sharpest, most vital performances of those works you're likely to hear. They didn't get a lot of local attention during the short time they were together, and now, being graduate students and budding professors, they've scattered across the country, but they've vowed to get back together a few times a year, to keep working, keep playing. In 10 years, if they can stick together, this could be the Next Big American Quartet. If you were lucky, you heard it here first.