I'll let Paul Cantrell describe Impromptu D899 No 4 (a.k.a. Op 90 No 4, in A flat minor): "This is a very familiar piece (to piano aficionados, anyway) — but you’ll find Don’s performance a little refreshingly unfamiliar. It’s not a wild departure from custom, but there’s just a subtle tip in the balance in his performance that makes the feeling of the piece quite different. In the last entry I mentioned the question of foreground and background. When most pianists play this piece, they put the right hand squarely in the foreground: what you hear is a series of speedy cascades down, a fun bit of finger gymnastics. But when Don plays it, he balances foreground between the left and the right, and what emerges is the slower underlying chord progression. Instead of a nervously flitting thing, it becomes a smoothly unfolding one. That reading brings us to what is to me the essential nature of Schubert: a tiny thing with a vast interior, a world opening from a single moment."