C.P.E. Bach's Piano Sonata in A comes from 1765, a few years before C.P.E. would leave Berlin to travel to Hamburg.
One of the main things that stands out in the first movement of this sonata is the continual and virtuosic use of arpeggios. (mn.5-7)
The next thing to stand out is the use of a pedal point. (mn. 17-20)
Though this movement is not in sonata-allegro form, the use of arpeggios and pedal points helps identify key centers that are not to far from what one would expect such as E major.
Another noticeable feature of this movement is the linear nature of the bass line, that is sometimes hidden by the use of octave displacement.
I would like to compare this work to Haydn's Piano Sonata in F major, Hob.XVI:23 from 1773.
One immediate difference is Haydn's use of the alberti bass as an accompaniment figure. Also the linear nature of much of the melody contrast much of C.P.E.'s use of arpeggios
Haydn also uses a fuller accompaniment with the use of thirds as well as trills.
I chose this piece because, honestly, it is one of my favorite pieces of classical music. The first movement is just a pleasant A major.
"Hamelin plays C.P.E. Bach - Sonata in A, W.55 No. 4 Audio + Sheet music" YouTube video, 1:07. Posted by "madlovba3," upload March 16, 2012. video.
"Piano Sonata Hob.XVI:23 N.1 Haydn Allegro Moderato+ sheet " YouTube video, 3:41. Posted by "2hyeok," upload November 24, 2011. video.