Bayer’s ‘Flexible Sky: Music for Guitar and String Quartet’ features three such string works, two written during the classical and early Romantic eras by Haydn and Joseph Ignatz Schnabel, with the third a premiere recording on CD by the noted jazz and improvisation music performer Wolfgang Muthspiel (b. 1965).Guitarist Han Jonkers, who worked out the transcriptions and cadenzas for the Haydn work, is featured in the company of the Casal Quartet, the prize-winning Spanish ensemble founded in 1997."A sonic signature entirely its own," (NYTimes on the Casal Quartet)