Time and again in the summer months, you hear classical music concerts discussed with an air of impending defeat.

We're powerless over the weather, say management types behind the scenes. The Mann Center sweltered this summer. In chilly Vail, the Philadelphia Orchestra's Brahms Symphony No. 4 had to be halted minutes after it began due to pelting rain. The Berlin Philharmonic was drowned out by rain this summer in one of its few outdoor outings. And with picnicing audiences, how much listening really goes on? It's a summer concert, after all.

So you're right to wonder what planet the Philadelphia Orchestra's music director-designate Yannick Nézet-Séguin was speaking from when he said summertime compromise simply isn't necessary. Once the Brahms was resumed in Vail, he said, the performance's frisson was fabulous. And what of the single rehearsal allowed for most concerts? Your priorities are different, he says. He tells musicians to ignore previous rehearsal markings in their scores and just be in the moment.

"You just do it. There's a different architecture to rehearsals," he said, "but that doesn't mean compromise." If the purpose of a rehearsal is to take the orchestra from point A to point B, point B had better be closer than it is in a typical Kimmel Center concert.

"In many countries around the world, having a summer festival doesn't necessarily mean that you perform outside," said Lang Lang, who flew to the United States for a single Saratoga concert. "But it's wonderful for us to get some fresh air. Sunlight. Vitamin D! You have many new audiences. Ticket prices less. This is more relaxed. I don't see compromises here."

Even before he got famous, then-Curtis student Lang Lang was seen at the Mann - in the audience. Some of Nézet-Séguin's hottest Montreal concerts, to judge from Canadian radio broadcasts, have been semi-outdoor. Reportedly, his Saratoga performance of Jennifer Higdon's intricate Concerto for Orchestra exceeded his expections, and the composer's. Summer music can be top-notch.

If that happened all the time, imagine the possibilities. Audiences would leave happier. The orchestra would be more happily challenged. And maybe the overlap between the Philadelphia Orchestra audience at the Kimmel Center and at the Mann Center would not be minimal.

One barrier for the Center City crowd is artistic quality. The Mann Center, which now has a congenial host in CEO Catherine Cahill, had a clear-cut success this summer when the exciting Chinese conductor Xian Zhang led the Philadelphia Orchestra in Beethoven's Symphony No. 9. But much of the rest of the classical season seemed ritualized with the usual retreads, fireworks, and concerts that, on paper, seem only half interesting, such as the tribute to film composer John Williams.

Lowering the brow may create wider appeal, but while such concerts bring momentary success, how do you build a consistent, loyal audience with a diluted experience?

In fact, audiences can be fair-weather friends, literally: Weather easily discourages those who also are daunted by access issues. In Saratoga, the problem is finding a hotel room during track season. Tanglewood has similar challenges. But the Mann Center really isn't far from Center City; I bike there in as little as 25 minutes, and though I was once one of the few doing so, bike racks are now full at Philadelphia Orchestra concerts, suggesting an encouraging trend in audience demographics.

But bicyles aren't for everybody. Classical music audiences are older. And without a car, the Mann Center shuttle from Center City can turn into a multi-hour commitment, with departures starting about 6:20 p.m. for an 8 p.m. concert, compared with Chicago's Ravinia Festival, which is a 40-minute train ride from the Loop.

As always, though, all these issues are trumped by concerts with event status. Many lessons can be learned from New York's just-ended Mostly Mozart Festival, admittedly an inexact comparison because it's indoors, but otherwise a textbook summer series that a bit more than a decade ago was on the brink of being shut down, so tired was the programming, so routine were the performances.

The solution was to raise the brow. Up-and-coming conductor Louis Langrée was hired as music director, giving the festival vision and backbone. The acoustics of the primary venue, Avery Fisher Hall, were addressed by extending the stage into the audience area, creating better sound and more physical immediacy. Choreographer Mark Morris - an event unto himself - began making regular visits. New pieces by Magnus Lindberg and Osvaldo Golijov were premiered. Operas were presented in fully or semi-staged form. Today, Mostly Mozart thrives.

Similar attempts have been made over the last 12 years to spruce up the classical end of the Mann Center, but they often didn't go the extra mile. Operas imported from various places (including Houston) looked like make-do affairs and didn't sound so good over the Mann's sound system. A big road not taken was signaled by a 2001 all-star two-night stint of Stephen Sondheim's A Little Night Music that suffered greatly from being under-rehearsed; nothing like it was attempted again. One of the stars, the late Irene Worth, looked at the rehearsal schedule and exclaimed. "How do they do Mahler?"

Well, the Mann Center once had Charles Dutoit as its music director, and he was the kind of conductor who could pull off Mahler symphonies - somehow - in limited rehearsal time, not to mention Shostakovich's Symphony No. 10. Such artistic guidance is missed.

June's Philadelphia Orchestra Stokowski Celebration, conducted by Nézet-Séguin, was a big step in the right direction. Yes, it was indoors (in a celebratory return to the Academy of Music) but it put standard-repertoire programs in a fresh frame, as a remembrance of the brilliant, eccentric, roguish Leopold Stokowski. Programs were in ornate 1912 style. Each concert had a brief video prelude. Those are small things, but you listened with new ears. Artistically, it was excellent. Also important, it was fun. And that's what makes a trump card, in any season.

Contact music critic David Patrick Stearns at dstearns@phillynews.com.