Book of Horizons, the fifth CD from California's Secret Chiefs 3, is an enigmatic, shape-shifting survey of contemporary musical styles. Thrilling, visceral, and impossible to grasp in a single sitting, it encompasses Middle Eastern folk melodies, free improvisation, contemporary classical music, spaghetti-western soundtrack music, and the heaviest of heavy metal.

It's hard to imagine that it's the product of a single brain, but composer, multi-instrumentalist, and bandleader Trey Spruance says this kind of genre-hopping has fascinated him ever since he was a guitar-playing kid in his very first band.

"When I was 15, I was in a death-metal group, and we had this idea that we were going to play a bunch of ska tunes for a bunch of metalheads," he recalls on the line from his Bay Area home. "We just had this idea, you know: 'Okay, we're going to play this ska music, and that'll be amazing.' Half of the audience hated us, but there was definitely a joy in confronting that wall between styles."

Spruance laughingly dismisses his early exercise in perversity as a "juvenile expression" of his interest in mutant sound, but it's worth noting that his beginner's band was called Mr. Bungle. Fronted by the hyperactive, charismatic singer Mike Patton, that outfit soon went on to achieve cultlike status among listeners who liked their hardcore grind served up with a side order of theatrical chaos, and Spruance's appetite for sonic excess has not diminished over time.

He has, however, found some ingenious ways to harness his somewhat manic energies. Book of Horizons, for instance, is being sold as a Secret Chiefs 3 record, but it's really the product of six different bands: Forms, Ishraqiyun, Traditionalists, the Electromagnetic Azoth, the Holy Vehm, and Ur. Each has its own identity: Ishraqiyun, for instance, reflects Spruance's interest in Persian, Afghan, and Iraqi music, while the Holy Vehm is an over-the-top continuance of his early fascination with all things loud and cryptic.

This sounds like a studio-only conceit, but Spruance swears that each subproject has its own independent existence, and adds that several will be releasing their own CDs soon. "We're halfway through tracking three records for three of the bands," he says, "as well as simultaneously working on the next Secret Chiefs record. Essentially, what's happening is that the idea behind this band keeps on expanding."

Given that on Book of Horizons he's credited with playing rabab, saz, santur, cheng, bass, microtonal guitar, sitar guitar, electric guitar, acoustic guitar, organ, Clavinet, piano, electric piano, tack piano, sampler, various synthesizers, and a truckload of small percussion instruments, it's clear that Spruance needs this many projects just to utilize his varied skills. Less immediately apparent, however, is how he plans to present this enormous spectrum of music when Secret Chiefs 3 headlines Richard's on Richards on Sunday (January 8).

Spruance notes that on previous tours the Chiefs tended to play three different sets, in three different instrumental configurations. On this outing, however, he's presenting a kind of greatest-hits overview, accompanied by a pared-down cast of the musicians who helped him make Book of Horizons.

"Basically, we're doing cover versions of all of these different songs from these different bands, and doing them much more succinctly than we have in the past," he says. "I didn't want to half-way do the different-bands idea; it's better to just go out there and play, at least until we can get it together to actually do the separate-band thing."

He adds that although he'd need a 120-piece orchestra to realize all of his musical ideas, he's going to explore as many of them as he can within the somewhat compressed format of his touring sextet, which includes noted improviser Eyvind Kang on viola, Timb Harris on violin and guitar, Shahzad Ismaily on bass, Jai Young Kim on keyboards and guitar, and occasional Tom Waits sideman Ches Smith on drums. How, exactly, they're going to get from the filmic pomp of Ur's Exodus-theme cover to the venom fountain that is the Holy Vehm's "Exterminating Angel" is anyone's guess, but Spruance is convinced that neither his accomplices nor his listeners will have much difficulty making the leap.

"I just feel that stylistic restrictions are irrelevant, and they've always been irrelevant," he says. "But at the same time the differences between things are what is beautiful. So you might rebel against being put into a box as a musician and want to break out of that, but at the same time there's nothing better than trying to really understand how something as specific as, say, Persian music works.

"I'm also angered by how little of themselves or their consciousness musicians are putting into their music," he continues. "And I'm not just talking about all those bad punk-rock bands, although I don't accept that as a valid expression of anything. You have to put something very deeply connected to yourself into your music or else it's not really working-unless it's just for fun, and then it's fine."

Spruance, at least, has found a way to put all of himself into his music and have fun. Although he's interested in the occult aspects of music, in the way that it can be a vehicle for healing, revelation, or communion with the infinite, he's still that ska-crazed teen punk at heart-and, in his world, anything goes.

"I've stopped caring about what time signature anything is in or what key it's in, and I'm really happy about that," he says. "It's like genres: you don't really need to think about them so much. Music doesn't have to be like that. You do have to learn these things; it's important that you understand how the different kinds of feelings that you want to express will affect how you create your music. But getting to the point where you can let go of all the theory is great."

Secret Chiefs 3 plays Richard's on Richards on Sunday (January 8).