It must have seemed a great idea at the time. Having Philip Glass write a set of songs based on lyrics by Laurie Anderson, David Byrne, Paul Simon and Suzanne Vega makes a lot of cultural connections, not only between the worlds of popular and classical music, but also within the more eclectic art circles of Manhattan. Add a cast of performers ranging from Linda Ronstadt and the Roches to the Kronos String Quartet and Douglas Perry, and "Songs From Liquid Days" (CBS FM 39564) looks like a real musical breakthrough.

So why does it sound like such a pretentious blunder?

It's not as if the composer had gone slumming for the project. Glass, after all, found acceptance in the arty circles of rock music long before the classical establishment caught on to his compositional style; the potential for a pop crossover was there long before this project began splashing names around. Nor has Glass decided to play to the cheap seats in hopes of finding a mass audience. There are more overt rock elements in his sound track to the Paul Schrader film "Mishima" than there are here. Stylistically, "Songs From Liquid Days" settles solidly into the art song tradition. Which, ironically enough, is exactly what goes wrong with this recording.

Taken from a compositional viewpoint, the art song overtones pose few problems. The lyrics, by and large, are witty and perceptive; the only clunker in the lot is Paul Simon's laboriously whimsical "Changing Opinion," but even that manages to sound better than it reads.

The settings themselves are a bit more problematic. Melody may not be Glass' strong suit, but he does know how to write for voice. As with the best art songs, the focus here isn't on the singer, but on the song as a whole, and Glass is a master at matching vocal demands to the sound of the ensemble. Considering his fondness for stretching structural ideas across the broad canvas of an entire piece, that is quite an asset, as it affords him the sort of small-scale focus art songs demand.

But that overriding need for organization stiffens the general sense of the songs. "Forgetting," for example, bounces between its major- and minor-key motives with an obviousness that verges on the didactic. On the other end of things, there's "Changing Opinion," which opens with a joking allusion to Beethoven's "Moonlight" Sonata, but underplays the punch line so completely it might as well have been left unplayed.

Still,sk,3 these are minor points compared with the problems of performance. Bluntly put, the weakest aspect of "Songs From Liquid Days" is the singing. Not all of it, mind you. Perry is perfectly wonderful with "Open the Kingdom (Liquid Days, Part Two)"; Janice Pendarvis, who has sung backup with both Talking Heads and Sting, finds just the right balance between art song and soul singing in "Lightning."

From there, though, it's downhill. Bernard Fowler very nearly hits the mark with "Changing Opinion," but his jumps to falsetto are far too obvious to be convincing. Linda Ronstadt underplays her part, her thin tone sounding altogether too prim and proper throughout "Freezing." The saddest fate of all befalls the Roches, whose unadorned high harmony seems embarrassingly girlish against the glossy textures of "Liquid Days." When Ronstadt and the Roches get together for "Forgetting," the combination is a carnival of inadequacy, too painful for any fan to hear.

It's tempting to blame CBS for encouraging the sort of crossover effort that would bring such inappropriate talent into play, but the fault lies as much with Glass for being unable to understand how poorly the voices fit, or how to recast his compositional concepts to fit rock devices. The latter is an important point, for the musical vivacity of rock and its relatives has much to offer the imaginative and technically attuned composer.

Take, as an example, Scott Johnson's "John Somebody" (Nonesuch 9 79133-1). Existing less as a score than a realization on tape, "John Somebody" starts off as a fragment of speech that has been carefully edited down to a series of looped phrases, with each carefully cropped repeat setting up its own ostinato pattern. But where Johnson diverges from mere musique concrete is in his ability to translate these snippets of sound into melodic themes and develop the composition from there.

Because Johnson composes from the rhythmic ideas inherent in his taped fragments and fleshes out his ideas with electric guitars and synthesizers, it's tempting to lump him in with such rock experimenters as Holger Czukay and Brian Eno. But there's more going on here than just happy accidents: Johnson's structures hold up under the most critical analysis. In that sense, the rock influence of "John Somebody" is as invigorating as were the jazz overtones of Milhaud's "Le Creation du Monde" or Stravinsky's "Ebony" Concerto, which, looking down the road, suggests that even if Philip Glass' "Songs From Liquid Days" doesn't quite work, at least it's on the right track.