An adaptive output-feedback control design technique is proposed for a class of feedforward systems with input-to-state stable (ISS) appended dynamics in a block triangular (feedforward) structure. The system contains uncertain functions involving all states with the assumed bounds on uncertain functions allowed to contain crossproducts of unknown parameters and unmeasured states. The control design is based on the dual dynamic high-gain scaling technique and introduces a novel adaptation dynamics and scaling dynamics to globally stabilise the system using output feedback. The ISS appended dynamics are coupled with all the system states and the input and the ISS Lyapunov inequalities also feature crossproducts of unknown parameters and unmeasured states. The proposed control design does not require any knowledge of magnitude bounds on unknown parameters.