We propose an adaptive output-feedback control design technique for a class of feedforward systems with input-to-state stable (ISS) appended dynamics and disturbance inputs. The design is based on our recent results on the application of dynamic high-gain scaling to state-feedback and output-feedback control of feedforward systems. In this paper, we further investigate the robustness properties of the dynamic high-gain scaling approach by introducing exogenous disturbance inputs and the ISS appended dynamics that are coupled with all the system states and the input. The designed adaptive output-feedback controller achieves bounded-input-bounded-state stability with respect to disturbance inputs and also provides a disturbance attenuation result.