If you knew that a musician widely regarded as the World's Greatest with his instrument was coming to your city, wouldn't you want to go? What if two such musicians were coming and playing on the same bill? Such was the treat in store for instrumental music fans as the David Grisman [ tickets ] Quintet joined Bela Fleck [ tickets ] and the Flecktones for an evening of astonishing musical prowess on April 11th at the Paramount Theatre in Seattle.

Grisman's troupe started off the show, and it was readily apparent within the first few minutes why David ''Dawg'' Grisman is frequently called the World's Greatest Mandolin Player. He easily glides between soft, expressive segments and the kind of lightning quick solo runs that would make Bill Monroe proud. His backing band provided some amazing virtuoso performances as well. In particular, flamenco guitarist Enrique Coria held the crowd awestruck during a truly magnificent solo in the Grisman standard, ''Dawganova''.

Since both Grisman and Fleck have their roots in folk music and improvised ensemble jamming, it was no surprise when, near the end of DGQ's set, Fleck strolled onstage with his banjo and traded some fiery licks with Grisman. To say that Fleck held his own in this company would be an understatement, and the sold-out Paramount crowd showed its appreciation as each member of the band took a solo run during the final number.

The second set, featuring Bela back with his usual partners, the Flecktones, pushed the night's display of musical virtuosity to even higher levels. Fleck has been named the Best Banjo Player so many years in a row that Guitar Player magazine has proposed ''retiring'' him from the survey and simply naming the award after him. Fleck's greatest strength lies in the amazing variety of sounds and tones he gets out of his banjos and his array of foot pedals. He can make a banjo sound like almost instrument he wants.

But this band is no one man show - indeed, bass player Victor Wooten is a prodigy himself. Wooten has won more magazine awards and reader surveys than any bass player one can think of. Ask any bass player - he may not be a household name, but everyone who appreciates the bass knows about him. His bass solo was yet another awe-inspiring moment of instrumental prowess in a show filled with them.

Another highlight was the percussion work of the Flecktones' drummer, Futureman. This was no ordinary drum solo - Futureman plays an instrument he created himself, which he calls a ''synthaxe drumitar'', and as far as anyone knows, he's the only person on the planet who can play the thing.

Near the end of the show, the Flecktones left the stage and Grisman came out to join Fleck as the two of them simply began improvising off of each other. The result was one of those magic stage moments that simply can't be matched in the studio. After this breathtaking display, the Flecktones came back out on stage and Fleck led the ensemble through the Flecktones standard, ''Stomping Grounds''.

Watching the enthralled crowd dancing in the aisles, it seemed at times that there was so much music, there were so many moments of incredible instrumental ability that it was sometimes hard to absorb it all. But leaving a concert with one's senses overwhelmed by massive displays of talent is not the sort of thing most music lovers would consider a problem.