Each time I've driven out to the Napa Valley's gigantic Castello di Amorosa during Festival del Sole, I've felt a nervousness that comes from spending one's life in grocery discount outlets, taquerias, nightclubs and thrift stores and then suddenly attending a classical performance at a $30 million castle in the heart of the Napa Valley.

And yet each time, that very daunting prospect of mingling fraudulently with well-to-do citizenry has been rendered completely normal by some unfathomably equalizing occurrence up at the giant castle in the hills.

In 2008, for example, violinist Joshua Bell gave a stellar performance with pianist Jean-Yves Thibaudet of Grieg's Sonata for Violin and Piano no. 3 at Castello di Amorosa. He then hopped off the stage, strolled down the aisle and hung out. Classical musicians do not generally "hang out." But there he was, doing just that—chatting with fans, charming old ladies, signing programs for young violinists and taking photos with members of the audience.

The next year, in 2009, the great soprano Renée Fleming appeared at Castello di Amorosa. Upon entering, attendees were handed a libretto, with the ushers joking that it was "not so you can sing along." Yet after a recital heavy on Richard Strauss and George Gershwin, Fleming invited the gathered audience in the castle courtyard to do just that—to warble, croon and croak along in their common-folk fashion as one of the world's most celebrated singers performed "I Could Have Danced All Night."

You don't get that kind of close camaraderie at Avery Fisher Hall or the Kennedy Center. But in the Napa Valley, I can only imagine that the visiting artists think to themselves, "What the hell. I'm at a 12th-century, Tuscan-style castle, it's kinda weird, and these people seem cool. I think I'll stand over near that cast-iron dragon head under the coat of arms and, you know, when in Rome, or Napa, or wherever the heck I am, do like they do."

Call it the magic of music, if you will, or call it the magic of Festival del Sole, which for five years has brought top-name talent and world-class food events to the Napa Valley. (A sister festival in Italy runs annually as well.) Festival cofounder Barrett Wissman, a former hedge-fund executive who usually strolls the castle grounds with wife and cellist Nina Kotova on his arm, is also principal owner of the esteemed booking agency IMG Artists, and, as such, the annual lineup pulls liberally from his roster. Sarah Chang, James Galway, Anne Sofie von Otter, Robert Redford and many others have appeared in past festivals.

Wissman, whom the Bohemian honored in 2007 with a Boho Award for the festival, hit a funny little snag last year when he pled guilty to securities fraud, agreeing to pay $12 million in penalties and to appear as a key witness against his former conspirators. Because of his cooperation with the New York state attorney general's office, Wissman has been able to jet-set in the manner to which he is accustomed, and Festival del Sole has continued undeterred—with cofounder Richard Walker usually mentioned in press materials instead of Wissman.

That tiny, behind-the-scenes detail notwithstanding, this year's festival is rich with talent, from Joshua Bell to Chris Botti to Kotova's dependable presence. Not to be missed is Nikki Yanofsky's July 21 show at the Castello. Yanofsky is an incredible 16-year-old jazz singing sensation who's more than earned the many comparisons to Ella Fitzgerald; seek her version of "I Got Rhythm" to see why. With sharp technical precision and creative improvisation, Yanofsky clearly has a gilded road ahead. There's not a bad seat in the house, so don't hesitate to opt for the less expensive tickets, and don't be surprised if some tiny little magical thing happens up at the huge castle on the hill to upend your expectations.

The Festival del Sole runs at various venues July 16–25 in the Napa Valley. Nikki Yanofsky appears Wednesday, July 21, at Castello di Amorosa. 4045 N. St. Helena Hwy., Calistoga. 6:30pm. $50–$125. Full schedule at www.festivaldelsole.com.

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