The budget of the Philadelphia Orchestra must be taking a beating in these last few weeks of Christoph Eschenbach's tenure. Extra money was spent on augmented firepower last week in Mahler's

Symphony No. 8

, with revenue lost on seats given over to choirs.

But artistic ambition is not one of those assets that figures easily into a business equation, and it shouldn't. This week's program assembled by Eschenbach - his penultimate as music director before leaving town on the orchestra's Asian tour - is stacked two-thirds deep with new scores. Prospective listeners apparently were repelled: About a third of Verizon Hall's seats Thursday night yawned before the performers unfilled.

Sadly unfilled, as it turns out, since Marc-André Dalbavie's

La Source d'un regard

arrived for a U.S. premiere, justifying itself in equal parts pleasure and importance.

With opening belltones played by harpist Margarita Csonka Montanaro, quick glances at Dutilleux and Stravinsky, hypnotic smears of sound, a sweetly mystical section, and a dronelike obsession centering on one pitch, Dalbavie's 16-minute work passes as a parade of quite captivating sounds and colors.

Aspects of it - melody, for instance - are so subtle they seem written in invisible ink. Even the occasional sonic jab, while menacing, is not jarring enough to disturb the work's incredibly transporting quality.

Jointly commissioned by the Philadelphia Orchestra Association, the Royal Concertgebouw Orchestra, and the Bamberg Symphony, it will probably stand - along with Sofia Gubaidulina's

Feast During a Plague

, led by Simon Rattle - as the most enduring contribution of the Eschenbach era to the orchestral repertoire. Curiously, neither Eschenbach nor the composer (who was present) took the opportunity to say anything about the work to the audience (even as a message from orchestra board chairman Harold A. Sorgenti in the program book trumpeted this custom as one of Eschenbach's initiatives).

Thierry Escaich's

Organ Concerto No. 1

, if not as urgent a score as the Dalbavie, had the unusual ability to be overwrought without growing oppressive. Written in 1995, its emotional center is a middle movement with one of the longest and most successfully sustained run-ups to a climax I can remember hearing. The composer - organist of St.-Etienne-du-Mont in Paris and a professor at the Paris Conservatoire - played the work himself, a master of dexterity and judiciously chosen tone.

Eschenbach occupied the second half of the program with a nervous and superficial Prokofiev

Symphony No. 5

. His flex-tempo treatment of the first movement so stripped the narrative of tension one could sense only perhaps half the reason for this being one of the most trenchant symphonic statements of the last century.