The Pittsburgh sound, in all its rich darkness

This is an unsettling time for the fabled Pittsburgh Symphony to be making a West Coast tour.

Molded by the notorious martinet Fritz Reiner, maintained and enhanced by William Steinberg, Andre Previn, Lorin Maazel and, most recently, Mariss Jansons, the orchestra has been led since 2005 by a troika -- Andrew Davis (artistic advisor), Yan Pascal Tortelier (principal guest conductor) and Marek Janowski (“endowed” guest conductor) -- each with his own repertoire and responsibilities.

On its website, the ensemble touts this unwieldy arrangement as “The team for the times ... an innovative model for artistic leadership.” But in January, when Manfred Honeck was chosen as the music director starting in 2008, it looked as if the troika may have been a temporary fix all along, a way to borrow time as the search for a traditional music director continued.

Still, the show has had to go on, and Friday night, Davis brought the Pittsburghers to Orange County.

There, at the Renee and Henry Segerstrom Concert Hall, it was reassuring to hear that the orchestra still sports a rich, dark overall sound -- rendered somewhat murky and boomy by the hall’s evolving acoustics -- and a glassy upper-string timbre that could be heard as far back as the Previn era.

Opening with Stravinsky’s “Pulcinella” Suite, Davis demonstrated that he can draw that sound even from a small ensemble, although his slowish tempos sometimes robbed the score of its sparkle, and a distracting sandpaper-like backstage noise intruded from the Toccata onward.

Next, the Pittsburgh sound slipped like a warm, fur-lined glove around the piano in Schumann’s Piano Concerto. The 25-year-old keyboard hotshot Jonathan Biss caught the swing of the finale especially well, displaying flowing, lovely colors and a brilliant yet clear technique.

This year marks the 50th anniversary of Sibelius’ death, and Davis contributed a Symphony No. 5 that made thrilling points at key moments: the mighty propulsive crescendo at the close of the first movement, for one, and the big repeating tune in the finale, which was supported by a hearty, thick middle-bass sonority, and ending, with its short, sharp chords reverberating with just the right amount of space between them. Yet the performance lacked an essential quality of mystery.

For an encore, Davis had the band rip with gusto through the Polonaise from Tchaikovsky’s “Eugene Onegin.”