In medium bowl, mix powdered sugar and water until smooth; stir in maple-flavored syrup. Add additional water, 1 teaspoon at a time, until thick glazing consistency. Dip cooled doughnut balls into glaze; let excess drip off. (If glaze disappears while drying, glaze may be too thin. Try dipping balls again, or thicken up glaze by adding a small amount of powdered sugar.) Place glazed doughnut balls on cooling rack; let stand until glaze is set, about 10 minutes.