This is number 17 from 20 Progressive Duets. It is true, a higher number implies more musical challenge. D-tune relates to the key (=D) and the fact that Guitar 2 has to detune the E to D. A smooth piece with a wink towards folk music. In this piece the accompanist gets some interesting tasks, a section of pizzicato bass and a melody in natural and artificial harmonics. The piece requires practice, yet playing is a rewarding experience.