Gavin Bryars: String Quartet No. 1 "Between the National and the Bristol" [1986]

Released on Three Viennese Dancers, Gavin wrote this about this piece:

"Until then I had never considered writing a quartet partly because, although a string player myself, as a bassist I found myself outside the quasi-privacy of such an ensemble. However, as a way of ingratiating myself into this closed world I introduced aspects of the double bass into the piece. The passage with cello and viola playing heavily in octaves in the bottom register, for example, simulates the sound of the bass, and extended solos in natural harmonics, such as those in the coda, are part of the bass's technique...
When I started to write the piece, my initial idea had been to write a quartet in which each instrument would relate to a composer associated with it as a player, the whole quartet serving as a kind of imaginary séance bringing them together. In this scenario the composers were Ysayë, Vieuxtemps, Hindemith (or Kupkovic), and Schönberg."

I believe this one is out of print, but you can find used copies here.