PITTSFIELD — Perhaps it's unfair to a string quartet to program it so soon after the Dover and Emerson quartets.

South Mountain closed its concert season Sunday afternoon with the Johannes String Quartet, whose well-balanced, robust but sometimes rough-hewn playing fell somewhat short of the predecessor groups' near-perfection of ensemble, tone and approach. The program of Mozart, Bartok and Brahms offered bone and muscle with the music's refining features only sketched in.

According to the program biographies, the Johannes, founded in 1998, is not a full-time quartet with other activities on the side like the Dover and Emerson, but four veteran players from other activities who get together to play quartets.

It's to the credit of South Mountain, which has just received the Chamber Music Society of Lincoln Center's extraordinary service award, that it gives newer and less-known ensembles a chance. Indeed, the young Dover, founded in 2008, made its debut last month in the five-concert South Mountain series. But the Johannes, named after Brahms, sounded more like four individual players than a wholly integrated group.

Even in Brahms. The program culminated in his Clarinet Quintet, a gorgeously autumnal work from Brahms' last years. As clarinetist, the estimable Richard Stoltzman was troubled by accumulating moisture in his instrument during the first two movements, and never quite attained consistency of tone, phrasing and attack. Reflecting this, the performance as a whole came across as uneven and sometimes aggressive.


Little things add up. In the middle of the rapid finale of Mozart's Quartet No. 22, K. 589, which opened the program, he suddenly slows the action for a lyrical interlude. It's one of those moments that should catch you by surprise, no matter how many times you've heard the piece, and take your breath away.

The Johannes performance slowed as it should but the surprise wasn't there. So went the performance as a whole. It was well played, with a nice rhythmic flair in the minuet, but the sensuous delight possible in this music was only hinted at.

There's a strange beauty, and mystery, in the stridencies, slides and silences of Bartok's Quartet No. 3, the most compressed of his six quartets. Though diligently played, the effects here were just stridencies, slides and silences.

The Johannes players are violinists Soovin Kim and Julianne Lee, violist Choong-Jim Chang and cellist Peter Stumpf. Among their present and past affiliations are the Boston, Philadelphia and Los Angeles orchestras.