Club-goers and radioheads know that pop play lists are dominated by a Miami-Manhattan axis. For the uninitiated, the inescapable "Miami sound" is a slick hybrid of Afro-Cuban polyrhythms, girl-group vocals and Top 40 gloss, with danceability as its highest priority.

Though the sound was pioneered, perfected and popularized by the Miami Sound Machine, perhaps the best examples of the style are the one-off singles mass-produced by all-but-anonymous trios of pop tarts, one-hit wonders with names like Expose' and Company B. But brand-name stars like Madonna and Jellybean have recently jumped on the Latin bandwagon, too, with some success.

Miami Sound Machine: 'Let It Loose' Miami Sound Machine started the wave last year with the "Conga" line of hit singles from its "Primitive Love" album. Having had a taste of platinum, the group returns with "Let It Loose" (Epic OE 40769), its second -- and, sadly, much safer -- all-English LP.

"Primitive Love" wasn't the work of neophytes -- MSM has recorded umpteen enormously popular records in Spanish. But now that crossover success has found it, the group seems to have retrenched, toning down the spice and suburbanizing its salsa.

The clearest evidence that the group has been denatured is right up front -- the LP has been released under the name Gloria Este'fan and Miami Sound Machine, a calculated marketing identity move that is symptomatic of the record's lack of distinction. Este'fan is a capable, professional pop singer, but hardly an instantly identifiable voice or persona. She fares much better with the upbeat tracks than the slo-mo ballads, where she strains for lounge-act sincerity, sounding like a Cuban Karen Carpenter.

Still, MSM comes up with some standout hooks, and even its tamed rhythms have more pepper than most radio fare. "Rhythm Is Gonna Get You" is propelled by a wordless Afro-Cuban chant, and "Betcha Say That" bobs along buoyantly, too. But the title track is shackled to a programmed rhythm where it should be loose and limber, and both "Can't Stay Away From You" and "I Want You So Bad" are sucked into syrupy swamps. The production, by "Emilio & the Jerks," is pristine but predictable.

'Who's That Girl': The Sound Track

Madonna is the bait for the "Who's That Girl" sound track (Sire 25611), but what her followers will find is four rush-job ready-mades and a slapped-together collection of stray tracks from other artists, none of which has much connection to what shows up on screen.

With the title tune, Madonna continues to court the lucrative Hispanic market, following up "La Isla Bonita" with another foray into Spanish 101, and if the truth be told, her Berlitz treatment does render the repetitiveness of the lyrics more lilting.

Most of the Miami-sound singers are patterning their giggly delivery after Madonna's trademark vocals, but here the role model is sounding more and more like her imitators. Her voice is electronically speeded up, smoothed, sweetened and split into Chipmunk harmonies, and she comes out sounding like a computer-generated clone.

The sparkless songs sound like outtakes from "True Blue," recycling hooks from previous hits -- "Causing a Commotion" incorporates lines and riffs from "Into the Groove," and "The Look of Love" swallows "Live to Tell" whole. Stephen Bray supplies his usual production polish, but his chiming, chugging settings are becoming formulaic.

Scritti Politti's "Best Thing Ever," an air-whipped confection of white-bread soul, is certainly the best thing on this record, and should hold some till its new LP appears. And Coati Mundi, an associate of tropical popster Kid Creole, chips in "El Coco Loco (So So Bad)," which percolates along cheerfully while he boasts comically about his "badness."

The rest is forgettable filler. The gratingly banal "Turn It Up," performed by Michael Davidson, one of Madonna's photogenic prote'ge's, is set to a soulless click track by disco corporation Stock, Aiken and Waterman. Duncan Faure contributes a toss-off called "24 Hours," which is like what the early Beatles might have sounded like if they had emerged from Studio 54 instead of Liverpool's Cavern.

Jellybean: 'Just Visiting This Planet'

John Benitez, a k a Jellybean, is an influential New York disc jockey and dance taste-maker who at one time was best known for dating Madonna and remixing (and promoting) her early singles. As a result, his own output and identity has since been overshadowed by her pop-chart preeminence. But Jellybean seems to address the identity crisis on his second solo LP, "Just Visiting This Planet" (Chrysalis BFV 41569) -- one of the songs asks the pointed musical question "Who Found Who?"

Now an independent producer with a multirecord deal, Jellybean makes "solo albums" the way Quincy Jones does -- he enlists the aid of musical friends and constructs a gleaming pop edifice. If the resulting record is sonically flawless, it's also clearly the work of a technician rather than a musician.

Since Jellybean built his career out of spinning and reworking other people's records, it's no surprise that his own work is a cut-and-paste collage of familiar sounds. "Am I Dreaming" sounds like Cameo's last few hits crossed with Jody Watley's "Looking for a New Love." Benitez has found three strong new singers: Elisa Fiorillo, yet another Madonna sound-alike, delivers the Miami spice of "Little Too Good to Me"; breathy Adele Bertei coos "Am I Dreaming"; and Steven Dante', a soul crooner in the James Ingram mold, pours vocal lava over "The Real Thing." All eight lengthy tracks are dance-floor efficient, but the words and melodies evaporate on contact.