As the Chamber Orchestra of Philadelphia's season nears its end, so does Peter Gistelinck's executive directorship of an orchestra that has maintained its niche in the long shadow of the Philadelphia Orchestra while outstripping others with its technological savvy.

Founded 50 years ago by Marc Mostovoy, the orchestra burgeoned with the 2001 opening of the Kimmel Center, seriously teetered amid the 2009 recession, but has rebounded from most, though not all, cutbacks.

Gistelinck, 52, a hearty, friendly Belgian, had to fight for the orchestra's existence - "and all of my successors will definitely have to fight," he said last week. "It's part of the job."

Gistelinck's departure for the Kalamazoo Symphony Orchestra, announced in late March, was a surprise, since his eight-year run appeared to be hitting a new high. About 80 live Chamber Orchestra concerts are available for sale and streaming in 50 Web providers. The current tally is 86,000 streams and downloads, expected to rise to six figures in 2015.

An additional 20 concerts will bring that total up to 100 in June. Sampled on Naxos Music Library, their sound quality is excellent, performance standard high. Important works by Michael Hersch and Steve Mackey aren't available elsewhere. In a separate enterprise, eight HD concert videos are free to patients in Jefferson Hospitals' GetWellNetwork.

Though the orchestra also plays pop programs with the likes of Josh Groban at the Mann Center, its core activities are on an upswing: Though high rental costs dropped it from 10 programs in the Kimmel Center's Perelman Theater to four in the 2009-10 season, it has inched back up to seven this season, with some repeated at Lincoln University. Subscription rates rose 5 percent this season, and single-ticket sales are up 12 percent.

"The little orchestra that can" is board president Susan Schwartz McDonald's nickname for the ensemble, which has a season budget of $1.8 million (the Philadelphia Orchestra's is $39.9 million.) Some orchestra musicians complain privately about the cuts of recent years, but won't comment publicly.

Thanks to Gistelinck's European orientation, major guest artists seldom heard in the United States - cellists Pieter Wispelwey and Jean-Guihen Queyras in past seasons, violinist Augustin Dumay next season - play Philadelphia. The charming Michel Legrand Harp Concerto, premiered this year, was an unexpected coup.

Part of that European orientation is due to the 2010 appointment of music director Dirk Brossé, a fellow Belgian and long-time friend of Gistelinck's.

The film Brossé: A Destiny in Music, to be screened at 7 p.m. Thursday at the Perelman, shows what an unconventional, magnetic figure the conductor is, especially next to his predecessor, classics-steeped Ignat Solzhenitsyn. (Brossé: A Destiny in Music does not mention the unsolved murder of his stepdaughter last summer; because the film was already shot, Brossé and director Jacques Servaes decided to dedicate it to her.)

On Sunday and Monday, Brossé conducts the orchestra in an all-Tchaikovsky program - next door to Verizon Hall, home to one of the world's great Tchaikovsky orchestras - but with the insights that come with one composer (Brossé - he slips his conducting appearances between composing film scores) in dialogue with another (Tchaikovsky).

At least in theory.

In execution, Brossé isn't the most considered interpreter. The four movements of his Haydn symphonies can sound like separate pieces rather than part of a whole. Aside from this season's one-off Verizon Hall performance with the Chamber Orchestra augmented by more players (some from the Philadelphia Orchestra), the quality of playing seems to be slipping. Programming can be pretty standard. The orchestra needs a deeper commitment from Brossé, but without Gistelinck in the picture, can one hope for that?

A key difference between Brossé and Solzhenitsyn: The latter insisted on four rehearsals per program (and still does when visiting); Brossé has three. Gistelinck points out that some major orchestras make do with one. "I am not pretending that's a good way of doing things," he added in an e-mail.

Also, the pecking order of its player pool is such that if the 33 core contracted players are busy with, say, Opera Philadelphia, the Chamber Orchestra turns to its sub list, which includes students.

Maintaining its niche means being the most fully realized alternative possible. That happens some of the time. It needs to happen most of the time.