The baptism was by wind yesterday at the University of Maryland.

Rolf Smedvig, of the acclaimed Empire Brass Quintet, creased his pleasant, boyish face into a frown as he listened to Scott Chadwick, 18, on the trumpet.

"You're playing pear-shaped notes," he said sharply. "You're going WHAH-WHAH-WHAH. That's a no-no in the business."

A score of students had gathered in Tawes Recital Hall to hear the quintet perform and to receive its collective wisdom at a clinic on chamber music. They called it a "plug-in" session.

Steve Conley, a music education major, plugged himself into Smedvig's seat to try his luck with a work by the Renaissance composer Palestrina. When he finished sight-reading, the trumpet virtuoso berated him for "terrible finger position" and "moving from side to side." His hand on Conley's shoulder, Smedvig counseled, "You've got to relax."

Afterward the young man looked a mite pale. "I was kinda nervous, but it was a lot of fun," said the slightly built senior. "It's a lot different from anything I've ever experienced, to play with a quintet like this. They're so talented. Me, I've always had a problem with my nerves."

Praised by music critics from Manhattan to Hamburg ("astounding virtuosity, immaculate attacks, prodigies of breath control," said The New Yorker), this quintet is one of a handful that gets star billing. Formed 11 years ago in the players' hometown of Boston, and encouraged by the likes of Leonard Bernstein and Michael Tilson-Thomas, it won the prestigious Naumburg Chamber Music Award in 1976 and the Harvard Musical Society Prize in 1980.

The five now play a daunting schedule of concerts and recording dates while holding down teaching duties at Boston University. They also coach players at the Tanglewood music camp in Massachusetts, and give about 30 chamber clinics a year from coast to coast. Along with the American, Canadian and New York brass quintets, the group occupies one of the more rarefied climes in classical music.

The reasons: Brass instruments are notoriously unforgiving, both technically and physically, and the combination of two trumpets, French horn, trombone and tuba has captured the hearts of very few composers.

"I'd say two-thirds of what we do is transcription," said French horn player David Ohanian, who, at 36, is the group's oldest member. (Trombonist Larry Isaacson, who just joined, is 24; Smedvig is 30; second trumpet player Charles Lewis Jr. and tuba player Samuel Pilafian are both 32.) "Most of what we do in its original form is either very early music or very late music. Starting with the classical period -- Mozart, Beethoven, Brahms -- there are just huge holes."

Thursday night, the ensemble blew a University of Maryland audience out of their chairs with a program of Bach (a trio sonata transcribed from string parts), Victor Ewald's "Symphony for Brass," Alvin Etler's stormy "Quintet" and a selection of adapted pieces from Handel to Cole Porter.

The evening was instructive of the lot of professional brass players. The fivesome took the stage in natty black tuxedos, like a group of dignified string players. But before long, torrents of sweat coursed from Lewis' broad forehead, while Smedvig wiped his mouth repeatedly on his nicely tailored sleeve, and Ohanian kept removing a valve to dump spit on the polished platform. It was not a performance designed to appeal to delicate sensibilities.

"These are very brash, macho instruments," Ohanian allowed.

Yesterday morning, the group appeared in matching tan suits and shoes to pass on knowledge to novices. "It was great," said 22-year-old French horn player Andrew Lance, after sitting in with the group. "Their control is so well developed, it's like fitting yourself into something that's been finely molded." Another young horn player, Cathy Freeman, agreed: "They're the most intense musicians I've ever played with."

The session over, Smedvig and Lewis made for the Holiday Rambler recreational vehicle that transports the group from concert to concert. "We don't come across many young musicians who would be able to make a living as performers," Smedvig said, as Lewis nodded. "In all the clinics we give in a year, maybe -- maybe -- we'll find just one."