A skilled colorist and an innovative explorer of acoustics and live electronics, Finnish composer Kaija Saariaho employs a wide variety of natural and synthesized sonorities in her uncompromisingly avant-garde chamber works. Incorporating computer technology with traditional instruments, Saariaho creates elaborate structures in which eerie twitters, haunting whispers, and occasionally frightening screeches unexpectedly emerge from more familiar timbres.

Friedrich Cerha (b. 1926) is revealed by this great 2-disc Kairos set to be one of the great composers of the late 20th Century, who deserves to be recognized alongside Xenakis, Ligeti, Nono, Stockhausen, and Boulez. Cerha was the 2012 recipient of the Ernst von Siemens Music Prize, the "Nobel Prize of music," and so his reputation and stature outside of Austria are belatedly coming to more closely match the esteem he enjoys in his own country. Cerha's own music has only been extensively documented recently, with a series of discs on Austrian neuemusik label Kairos, as well as recordings on the ECM, Col Legno, and Neos labels.

It's stretching the conventional, technical definition of the term to call Swiss composer Michael Jarrell's spoken monodrama Cassandre an opera, but that's the composer's description of it, and as such, it ought to be respected. It does consist of a musical narrative accompanying a verbal narrative, so even though it doesn't involve singing, it comes closer to standard opera than some pieces that are so designated.

Although Kairos’s rate of production has decreased in the past few years, the Viennese label still regularly releases discs of music by contemporary Austrian composers. This CD of two recent orchestral works by Friedrich Cerha, celebrating the composer’s 90th birthday, is a welcome addition to Kairos’s four previous albums of his music. While Cerha’s recent chamber music adheres to classical forms, his orchestral music from the same period eschews them, revisiting instead the principles laid out in his sound-mass works from the late 1950s such as Spiegel.

This new work by Spanish composer Alberto Posadas, composed from 2003 to 2007, is not a collection of string quartets, but rather a cycle of five quartets, meant to be performed as a whole with only brief pauses punctuating the parts, 52 minutes in all. It is performed here with energy and precision by the Quatuor Diotima, and recorded in January 2009 for Kairos.