IN THE LAST few years, Doyle Lawson and Quicksilver have ascended to the highest echelons of contemporary bluegrass. Their latest album, "Once and for Always," vibrantly parades their musical assets: impeccable and forceful musicianship, perhaps the finest harmonies in bluegrass and a seamless integration of traditional sounds with more modern stylizations.

Those polished harmonies remain the group's trademark and two a cappella gospel tunes, "A Lover of the Lord" and "When the Sun of My Life Goes Down," are showcases for the quartet's intricate arrangements and flawless execution. The harmonies are even more moving when heard in a sweet country tune such as the title track, where guest instrumentalist Mike Auldridge adds a weeping pedal steel guitar in plaintive support.

As smooth and versatile as the voices are, Quicksilver's music gains its color and momentum from the rolling drive of Terry Baucom's banjo work and Lawson's spritely mandolin. On Michael Murphy's "Carolina in the Pines," Baucom's sharp banjo and Lawson's brittle mandolin tumble alongside each other like two buddies, arm and arm, heading down a country road. ." DOYLE LAWSON & QUICKSILVER -- "Once and for Always" (Sugar Hill 3744); appearing Friday and Saturday at the Birchmere.