Not so on Thursday, when the sound design had a good night, and the debuting musicians, conductor Bramwell Tovey and pianist Orion Weiss, were particularly irrepressible.

Both are good candidates for the orchestra's regular Kimmel Center season, particularly Tovey, who was such an effortless, urbane talker in his introduction to Berlioz's Symphonie Fantastique (imagine Noel Coward rewriting an Anna Russell comedy routine) that the Philadelphia Orchestra shouldn't let him leave the city limits until he signs a multiyear commitment to the talk-and-play Access Concerts.

Conductingwise, Tovey delivers the goods. Not until after the concert did I learn that Tovey, now music director of the Vancouver Symphony, is also a composer and is at work on a major stage work for the Calgary Opera. His reading of Berlioz's Rakoczy March more than hinted at that extra dimension to his personality: Many conductors conduct that warhorse on autopilot, but Tovey alighted upon all kinds of sinister-sounding inner voices, and sustained its tension masterfully, thanks partly to cheeky but effective tempo accelerandos that suggested he and Berlioz were having a composer-to-composer dialogue.

Similar touches - underscoring of inner voices conveyed more-than-usual subversive activities - were heard in the Symphonie Fantastique, though that performance was bound to be less distinctive. With short rehearsal time and so many other Philadelphia Orchestra conductors having left fingerprints behind, interpretive ownership is hard to assign to any one of them (including whoever is on the podium at the moment).

Though the performance was superficially conventional, any number of passages that don't always sustain their line of thought in outdoor circumstances, such as the shepherd pipes in the sprawling third movement, worked just fine. Overall, Tovey's art solves problems of musical complexity with simplicity and elegance, though not so much that the final movement's "Witches Sabbath" wasn't allowed to get quite raucous.

The young pianist Weiss, a student of Emanuel Ax at Juilliard, couldn't help but inspire immediate sympathy, from having grown up in small-town Ohio with the first name "Orion." Now, that's emblazoned across his debut compact disc, which contains fine performances of Bach and Elliott Carter. Both on the Yarlung-label disc and live on Thursday, Weiss has a crispness that owes so much to Glenn Gould you suspect that at least some of his insights, however interesting, are secondhand.

Though Weiss wasn't always interesting or well coordinated with the orchestra in Beethoven's first movement, his big cadenza had such originality and variety that you wanted him to go on forever. His Mozartean legato in the second movement was the consolation prize when he didn't.