JASON'S REVENGE: The Grays performed an energetic show at the Mercury Cafe on Tuesday night, led by Jason Falkner, the original guitarist of San Francisco's Jellyfish. With that pop band's debut album (1990's "Bellybutton"), Falkner experienced critical acclaim in the U.S. and prosperity in Europe. But Jellyfish was supposed to be a collaborative operation, and his role was reduced as time went on. "I was excited to work with those guys. In terms of musical taste, we came from similar places," Falkner said before the concert. "When I joined, they said, 'We know you write and sing. We want you to bring in songs.' But I stopped doing it after the fifth flat-out rejection - they had no interest in sharing the songwriting spotlight. "That's why I left. We did nice shows and got talked about, and people said, 'You're like the George Harrison of the band.' No - he got a couple of songs on each Beatles record, I didn't get any. 'You're a fool, stick it out, maybe by the third record you'll be miserable but rich.' That meant nothing to me." So Falkner formed the Grays with Jon Brion, whose credits include Aimee Mann's solo album, and Buddy Judge, the other main songwriter. "Ro Sham Bo" is the band's debut release, and Falkner's power-pop skills are showcased on "Very Best Years" (check out the well-crafted harmonies). "But it's not a democracy," Falkner cautioned. "It's a mutual admiration, separatist process - a lot of 'I'm right and you guys are wrong."' Last month, Falkner heard the news - Jellyfish has called it a day, and the obligatory "musical differences" led to the split. "It's ironic," he laughed. "Let's just say that I didn't have a moment of silence when I heard about it."