When the grassroots movement underneath the Dave Matthews Band became a raging brushfire around 1996 or so, DMB was left in a rare and not altogether enviable position. Sure, they were raking in cash, but they were also left to straddle the divide between two opposing musical worlds the incredibly lucrative one of mainstream appeal, and its Bizarro equivalent, the world that wears inscrutability as a badge of honor.

It seems like DMB and amphitheater tours have always gone hand-in-hand; it was a little disconcerting to realize to nearly a decade has passed since I first witnessed the erstwhile Charlottesville, Virginia bar band on a summer stage. Yet, there they were, a little older but apparently no worse for the wear the core quintet of Matthews, violinist Boyd Tinsley, drummer Carter Beauford, bassist Stefan Lessard, and sax man Leroi Moore, accompanied by touring keyboardist Butch Taylor, essentially looking the same as they did last year, and the year before, and the year before that. There's some comfort, certainly, in the tried-and-true, but it's becoming increasingly clear that DMB is far from the same model they were in 1996, or even as recently as the turn of the millennium. Whether that's a good or bad thing depends entirely upon your point of view.

The recently released "Stand Up" is hardly the greatest entry in their catalog, although the number of times I heard it blasting out of SUV tailgates on the way into Hi-Fi Buys Amphitheater may seem to refute that. Unfortunately, in the case of Stand Up, and to an extent, its two predecessors, Busted Stuff and Everyday, DMB has allowed studio polish to cast a blinding glare, like a mirror in the desert sun, across the quirky yet dark ambition that ruled earlier releases like "Under the Table and Dreaming." And live, alas, the newer songs fare little better Stand Up offerings like "Dreamgirl," "Hunger for the Great Light" and "Stolen Away on 55th and 3rd" blurred past, struggling for any sort of musical identity. The standout of the bunchboth live and on discis "American Baby," which rules thanks to infectious but wistful pizzicato violin work from Tinsley.

The new mentality has also spilled over to older songs, as well: the gentle guitar strains that once announced the opening "One Sweet World" have been replaced, less successfully, by a lounge muzak-y keys and sax intro. Thankfully, the sultry rage of "Don't Drink the Water" remains undimmed, and "Dancing Nancies" roared lustily at full boil, propelled by Matthews' growling refrain and the rhythm of Beauford and Lessard, both clearly relieved at being allowed to tear into a meatier number.

The show found its best gear for the set closers "Jimi Thing" and "Louisiana Bayou," the former classic, the latter new, both boosted by an appearance from longtime friend Trey Anastasio. At play in one of their very best numbers and pushed by Anastasio's jamming on one of their newer tunes, DMB proved still capable of invoking summers long past, if only for a short time. In the end, in fact, it was that twenty-minute-or-so climax that brought the dichotomy between DMB's two worlds into the brightest light. The multiple textures and handworked feel of "Jimi Thing" recalled a band hungry to make it; "Bayou" showcased the less risky precision of a band that already has. And once again, which is the preferable model is a question each audience member had to answer for themselves.

Like the rest of Stand Up, it's not that "Louisiana Bayou" is a bad songbut to frame it in the context of the band's recent Rolling Stone cover, in which they appeared decked out in vintage baseball attire: it's just a little dispiriting when a band with home run power settles for the easy single to shallow left.