From the net of associations cast over the South Bank Centre's current American Independents festival, Tuesday's double dose of Purcell Room concerts yielded a small yet substantial harvest of songs and other pieces. Last week, for example, the Endymion Ensemble had programmed canonic studies by the naturalised Mexican (but US-born) maverick Conlon Nancarrow. In their 8pm recital this Tuesday, the Arditti Quartet continued the theme with a reading of Nancarrow's 1988 String Quartet, a work of nothing but canons. Likewise, while the Endymions had given us Charles Ives's transcriptions of his own "Ann Street" and "Like a Sick Eagle", two of this century's most likeable art-songs, the pianist Thomas Ades and the soprano Valdine Anderson, taking Tuesday's early-evening slot, performed the songs in their original form.

But there were unfamiliar works as well, including Phonemena for voice and piano by the veteran American experimentalist, Milton Babbitt, and major works by American pioneers of a different kind, John Cage and George Crumb. By now surely a classic, Cage's The Wonderful Widow of 18 Springs, for voice and tapped piano lid, seems to this pair of ears more serious and heavy-hearted at each new hearing. Valdine Anderson's tensile yet buoyant timbre was the perfect vehicle for the composer's rare imagination, and proved no less subtle in Crumb's even more challenging Apparition, which takes its text from the work of another American outsider, Walt Whitman. Plucking and rubbing the strings of the prepared piano, Ades delivered a precisely timed accompaniment to this haunting piece. Together, he and Anderson then relaxed in a neat little extract, "I am the wife of Mao tse-Tung", from John Adams's opera Nixon in China. Exultantly sang the fragrant Jiang Qing: "I sucked and pissed at the breast of history" - as indeed she did.

Dwelling on more elevated types of human intercourse - nothing less, in fact, than the conversational ideal that lies at the heart of classical chamber music - the octogenarian Elliott Carter in his recent Fifth Quartet has produced a work of fetching intimacy that links its scenes and acts into a single arch of invention. Throughout, while the textures, true to style, remained densely chromatic, the sound had the lightness and clarity that shines through all his late works. In places it recalled the fleet atonality of Ruth Crawford Seeger's 1931 String Quartet, heard earlier in the Arditti's programme. Casting even wider the net of association, Carter's final episode, a flurry of plucked strings exploding like a barrage of ukuleles, was enough to have made even Carter's mentor, Charles Ives, proud.

Ives's own work was here on show with a group of short piano-quintet pieces, Thomas Ades again playing heroically at the keyboard. Scales together and in many keys in Hallowe'en just added to the fun.

The evening's UK premiere, and a surprise return from a composer not often heard over here, was Roger Reynolds's Ariadne's Thread for quartet and computer-generated sound. A medley of many diverse elements of myth, it proved to be a journey of alluring sonic encounters, carefully combined into one of the best things of its electro-acoustic kind to be heard in a very long time.

Final concert in the series: Kronos Quartet play Partch, Ives, Hyla and Crumb: Tuesday 7.30pm RFH, SBC, London SE1 (0171-960 4242)

Nicholas Williams