The forecast was for 76 degrees and sun but the weatherman was way off on this one. As show time approaches, cool air and thick fog start rolling through the Berkeley hills, making this summer fiesta start to feel more like Halloween. But the flip side is that the foggy conditions add a more mystical vibe to the proceedings. This seems appropriate considering that STS9 is taking a big step up tonight, making their first headlining appearance at the legendary Greek Theater.

Since relocating from Georgia to Santa Cruz at the dawn of the century, the band has slowly but surely built a solid reputation as both a Bay Area and national favorite on the jam scene. Whether an instrumental band can ever really crossover to mainstream popularity is another question. “Our feeling is that this record could be for everybody… but then again, probably not,” says bassist David Murphy of the group’s new Peaceblaster album.

It’s a bold effort that captures the band’s live energy better than their previous studio work, while also going further in elucidating a socially conscious vibe with its song titles and sound bites. The album captures the band’s ability to mix deep grooves and infectious rhythms with a variety of shimmering tones and psychedelic textures to create compelling sonic landscapes that make everyone in a crowd want to get down. There’s probably no other band as skillfully able to mix samples with live instrumentation and make it all sound so organic.

A devoted core fan base has come to view STS9 as one of the most unique entities in music and would probably prefer to see the band’s scene remain on a more intimate level. But after you’ve been selling out small halls and theaters, the next logical step is to move on to venues like the majestic Greek Theater, a truly Greco-Roman style venue (as opposed to the LA Greek Theater) that has hosted the biggest names in music over the past four decades. Whether or not the band can fill it is less important than the opportunity to have some outdoor summer fun in a fresh setting. The upper bowl is sparsely filled but the pit and lower sections are packed in with fans from all over the Bay Area eager to see what the group has in store for this classic venue. Prefuse 73 offers an opening DJ set, but it doesn’t seem to particularly grab folks in the early part of this now chilly evening.

Rising DJ star Bassnectar is on the bill as well, so it’s a surprise when STS9 comes out next. The band opens with the new “Metameme” as keyboard wizard David Phipps conjures an array of psychedelia, while underrated guitarist Hunter Brown weaves nifty lines in the spaces between. Drummer Zach Velmer and percussionist Jeffree Lerner pick up the beat in unison, as if one four-armed percussion beast, synching in tightly with bassist Murphy. From the off, the group’s five parts interact seamlessly to create a sonic collective that seems to operate with one group mind.

Having played a fan club show at the much smaller Independent in San Francisco the previous night that featured more classic material, it’s no surprise that the band will focus on newer material here. But unlike pop bands whose fans come hoping to sing along to their favorite hits, STS9 is a group where the particular songs played seem less important than the overall energy the band summons.

“Aimlessly” dips back a few years to a more familiar groove, but it’s the new “Beyond Right Now” that really stands out. Brown leads the charge with his guitar riffs taking a more prominent space than usual to establish a bluesier vibe, while Velmer throws down a powerful beat. Lerner’s polyrhythmic percussion takes the rhythm to another level and the crowd tunes right into the groove. Later, the band uses the powerful new “Shock Doctrine” to close the first set with a darker, edgier sound than they normally bring in the closing slot. With the fog still rolling in and the extrasensory light show swirling, the song has a dramatic effect and the band closes the set on a triumphant note.

The surprise comes when Bassnectar then takes the stage to deliver a groovy halftime set, giving everyone the chance to enjoy his skills while already warmed up—no one’s sitting down during this set break. With screen shots offering a variety of visual stimulation to go along with his highly danceable and trippy beats, Bassnectar (aka Lorin Ashton) keeps the crowd moving and grooving. Having him perform during the set break is a brilliant tactic. His diversity stands out when he throws down sounds and visuals that conjure the Roaring ‘20s, giving couples a chance to dance a jazzy jig.

By the time STS9 returns, the crowd is really raring to go. The band could easily rest on their laurels by opening with a familiar favorite. But STS9 is all about boldly exploring new sonic territory, so it’s not surprising when they choose to open with three consecutive new songs. “Empires” starts off slow and spacey, giving folks a chance to get settled back in, a commendable move considering the show didn’t have a traditional set break. The jam builds slowly but seems like more of a warm-up number. It segues into “New Soma”, where Velmer’s dynamic lead drumming is balanced by some trance-y synth work from Phipps, before the sonic wave diffuses, then builds again.

“Hidden Hand, Hidden Fist” gets the crowd bumping, with a sublime mix of groovy textures from keyboards, guitar, bass, and samples all mixing together artfully for a smorgasbord of sonic delights. Phipps is the maestro here, conducting a psychedelic symphony over a big groove from Murphy and Velmer on what is one of Peaceblaster’s best tracks. “Rent” keeps things swinging; a new tune just a few years ago it is now a more familiar and dependable jam. But throughout the set, whether a song is newer or older seems not so much a concern as the fog and spacey light show continue to enhance the vibe.

The new “Peaceblaster ‘68” builds the energy back up again, with one of the album’s tightest grooves, which then segues into the more futuristic sounding “Peaceblaster ’08”. It all builds into a huge finish with a dazzling performance of “Inspire Strikes Back”, one of the top tunes from 2000’s Offered Schematics Suggesting Peace. The band builds an epic and ecstatic groove, with guitarist Brown delivering some of his most nimble fretwork in what has become a perennial crowd pleaser.

Longevity in the music business is established by bands that are constantly seeking to move forward instead of being content to re-hash previous success. Few bands are confident enough to play eight tracks from a new album in one show, but for the sonic explorers of STS9, it’s just testament to both the quality of Peaceblaster and the adventurous spirit that brought them this far in the first place.