I put on two Notebooks to check out the actual usage of the
Piano. A 14″ Notebook and a 15.4″ Notebook:

You see the 14″ Notebook quite suitably rested on the
Piano, but the 15.4″ Notebook seems a little big and spills over the speakers’s
projection area.

Update: The 2 speakers of PIANO-101 can be pulled out to fit a 17″ Notebook however…