Most Americans probably paid little attention to rap music before 1990. Then came the multi-platinum blockbuster albums by M.C. Hammer and Vanilla Ice, the network TV deals for the Fresh Prince (prime-time sitcom) and Kid 'n Play (Saturday morning cartoon), and the runaway controversy surrounding the foul-mouthed and minimally talented 2 Live Crew. Quincy Jones has blessed the music. Even the Pillsbury Doughboy started bustin' rhymes in '90.

Many people no doubt dislike rap. But everyone must acknowledge it as a dominant element of the American youth culture. After a decade, hip-hop is no longer an underdog art form.

The thing to watch in 1991 and beyond is how rap handles it success. The heart of hip-hop, after all, isn't Hammer or the Fresh Prince or even Luther Campbell. It's the rapper who hasn't sold 8 million units, who doesn't have his own sitcom, who hasn't been thrust into the role of First Amendment martyr. It's the groups such as Digital Underground, Stetsasonic, Gang Starr and EPMD, simply kicking it for the fans.

Digital Underground: 'This Is an E.P. Release' If any rap band seems poised for breakaway success, it's the Oakland outfit Digital Underground, whose million-selling debut "Sex Packets" was one of 1990's funkiest albums. If fame comes, though, it will surely be on DU's terms. Its new 33-minute EP, "This Is an E.P. Release" (Tommy Boy), concludes with the most overt and respectful acknowledgment ever of hip-hop's funky forefathers. "Arguin' on the Funk" features front man Shock-G trying to convince his alter ego, Humpty Hump, of the historical importance of George Clinton and Parliament-Funkadelic, whose music DU liberally samples. "You've got to give credit where credit is due," he says.

"E.P." represents a holding pattern for the band. It contains three remixes of earlier material and three new tracks, two from the upcoming Dan Aykroyd movie "Nothing But Trouble." None of the originals is as stunningly groovy or lyrically imaginative as "Humpty Dance" or "Doowutchyalike" from last year. But the leadoff single "Same Song" has a tasty organ solo, "Tie the Knot" wittily butchers "The Wedding March," and both feature the sublimely goofy Humpty Hump, the band's bread-and-butter voice. Digital Underground is one of hip-hop's most consistent sources of solid dance beats and good humor.

Stetsasonic: 'Blood, Sweat & No Tears' In the three years since Stetsasonic's last album, DJ Prince Paul has become a star producer and remixer, primarily on the strength of his quirky beats for De La Soul. But the hottest cuts on the new "Blood, Sweat & No Tears" (Tommy Boy) weren't produced by Paul, but by drummer Bobby Simmons. "No B.S. Allowed" is driven by a powerfully slamming snare, and "Speaking of a Girl Named Suzy" has an unusually brisk swing. Otherwise, this isn't a cutting-edge production.

What Stet offers in abundance, though, is positive vibes, largely thanks to lead rapper Daddy-O. With sexual distrust and loathing such common themes among male rappers, it's refreshing to hear Daddy-O deliver a simple, genuine love rap (with pet names and everything) called "Walkin' in the Rain." Even "Girl Named Suzy" is a pleasant surprise. Starting out as a typical tale of a pliant groupie, the rap ends with a grateful recollection of the time Suzy woke up the tour bus driver on an icy road and saved everybody's life. "She may be a groupie but we love her to the max," the guys say. A remix of the band's 1987 anti-apartheid rap "A.F.R.I.C.A." was probably included to remind the world that Stet was Afrocentric before it became trendy. Still, the sentiment is solid.

Daddy-O could stand to rethink his use of the put-down "faggot MCs," and he's a little quick to charge the government with attempted genocide. But these are blips; Stetsasonic doesn't stew in racial paranoia or macho bull.

Much of the fun in "Blood, Sweat & No Tears" comes from its celebration of early hip-hop, with Daddy-O gleefully dropping a couple of "old school" phrases ("and ya don't stop," "on and on and on and on"). In "Do You Remember This?" the band provides another veteran group, the Force M.D.'s, a platform for high-spirited harmonizing. There's even a touch of human beat box. Pioneer rappers Kurtis Blow, the Fantastic Five and the Cold Crush Brothers are graciously mentioned. Not only is this one for the fans, it's for the fans pushing 30.

Gang Starr: 'Step in the Arena' The Guru is part of a huge wave of Muslim rappers, but he doesn't pump much Nation of Islam ideology on "Step in the Arena" (Chrysalis), his debut album with partner DJ Premier. And despite the name Gang Starr, the Guru isn't into ultra-violent gangsta-style storytelling. This is smooth, socially conscious hip-hop for the thoughtful listener.

Unfortunately, though the Guru is intelligent, agile and earnest ("Any means necessary, I'm going all out, before the rains bring the nuclear fallout"), he isn't often exciting. "Just to Get a Rep," for example, is a noble anti-crime lyric. But as the title suggests, it doesn't dig deep into the crisis of violence in urban America. Like Daddy-O, the Guru isn't afraid to show romantic vulnerability, as in "Lovesick." But he doesn't make you care. His understated delivery takes a while to warm up to.

The Guru's standout piece is "Check the Technique," a breathless boast with metaphors butting each other out of the way. First he's a scientist (and his competitors are "protozoa"), then he's a neurosurgeon, then a defensive end, then a punter. That's just in the first two minutes. Here, he makes you pay attention.

Premier, as keeper of the groove, rarely does anything to startle the listener. It's fine that his tastes lean toward mellow soul, but couldn't he construct his samples more ambitiously than in four-bar or eight-bar loops?

EPMD: 'Business as Usual' The third album from the duo EPMD, "Business as Usual" (Def Jam/RAL/Columbia), seems like a first try by a couple of N.W.A. wannabes. The front cover has Erick Sermon and Parrish Smith coolly facing a pack of gun-toting white cops with dogs. Song titles: "Hardcore," "Rampage," "Manslaughter," "Hit Squad Heist." They flat-out steal an N.W.A. line, "coming straight from the underground." For this, Def Jam honcho Russell Simmons spent a reported $1.7 million to sign EPMD?

Sermon and Smith spend so much time rapping about their guns and their reproductive organs, you start to realize that, in their minds at least, they are one and the same. At one point, Sermon actually talks of sliding his 9-millimeter down the front of his pants. There's something sadly desperate about the way he spits out the couplet, "I'm far from a chump, I'm hard core like Brooklyn. Mess with me and get your manhood tooken."

Musically, EPMD does manage to land a couple of solid punches. "I'm Mad" is a frantic drive, in the style of Public Enemy's Bomb Squad production team. "Jane 3" has a slow, funky whomp, something easy to concentrate on while ignoring a ludicrous criminal-sexual adventure.