Mozart -- to the ninth degree

A concert containing nothing but Mozart piano concertos can cut two ways for an audience.

When heard or overheard casually, a menu like this goes down easily. But if you are actively concentrating on the music -- and the performers are just ambling routinely through the scores -- it can be a long, long evening.

Jeffrey Kahane and the Los Angeles Chamber Orchestra pulled off such programs successfully many times on the way to a rare complete cycle, but in that case, there was the added excitement of witnessing a stunt in progress.

For British pianist Howard Shelley, conductor Jorge Mester and the Pasadena Symphony Orchestra, though, there was no marathon involved Saturday night at the Pasadena Civic -- just this one program of three concertos. And they performed it with style and vigor.

The concertos they chose were Nos. 9, 18 and 27 -- and the decisive reason, one suspects, is that all are multiples of 9. No. 9 was a breakthrough for Mozart, his first mature piano concerto; No. 18 pushes his control over the genre a little further. No. 27, his last, is the most memorable of the three; the basic material becomes even simpler (you can imagine the tune of the Rondo being sung by Papageno in “The Magic Flute”), but the development ever more eloquent.

Shelley, who has roughly 80 CDs in print and also works regularly as a conductor, is a marvelous Mozart pianist -- flicking off all kinds of crisp accents and nuances in the outer movements of each concerto, handling the slow ones limpidly yet with a firmness of touch that prevented any outbreaks of torpor.

He had some interesting ideas of his own along the way -- the deftly gauged ornaments and embellishments in the first and second movements of No. 27 and a fascinating plunge into melancholy in one repetition of No. 27’s otherwise cheerful Rondo tune.

Mester’s introductions and underlying support were always alive, graceful, zipping right along, beholden to no doctrine -- and the balances between the piano and the chamber-sized Pasadena Symphony never tilted too far in either’s favor. No one took Mozart for granted, which was great for casual and intent listeners alike.