BIG BIRTHDAY: American composer Elliott Carter turns 100 this year and is still going strong. Naxos celebrates with this first of two volumes dedicated to his most seminal works, the string quartets. No. 1 moved Mr. Carter into the “modern master” category more than 50 years ago with its juxtaposition of spaced-out astral sounds to scurrying strings, both interrupted by syncopated stabs of energy. No. 5, composed in the 1990s, is much the lightest of the set, full of graceful inventions, but don’t expect easy listening.
 
YOUNG MASTERS: Naxos seems intent on cornering the market on great young quartet ensembles, too. The Pacifica already has a reputation as one of America’s most promising, and it plays gorgeously on this label debut. The group emphasizes Mr. Carter’s late-Beethoven-like spirituality, but it can get down and dirty when it needs to.

THE BOTTOM LINE: Likely to prove the best recording to date of one of the most influential quartet cycles of the 20^th century.