Solo for Viola d’Amore by Georg Friedrich Haas performed live by Garth Knox in Graz.

This is the second half of the piece. In the final section, the sympathetic strings are plucked and bowed directly, an unusual and striking effect. These are the second set of strings on the viola d’amore, usually not played directly, only there to resonate passively. In this piece they are amplified, and controlled by a volume pedal.

G. F. Haas – Blumenstück (2000).
after texts from “Siebenkäs”

For choir (32 voices 8×4), bass tuba, and string quartet
Performed by Tom Walsh on tuba, the Quintett Rigas Kamermuziki, and the Latvian Radio Choir, Wolfgang Praxmarer conductor

Austrian composer Georg Friedrich Haas (b. 1953) truly experiments with sound. His extraordinary constructions of micro-intervals and pure harmonics create beautiful and opalescent soundscapes that move in ways that seem at once mysterious and obscure.

Here is the String Quartet No. 2 [1998] played by the Kairos Quartett.