The synchronous reluctance motor (SynRM) is gaining popularity for general purpose drivers, where the sensorless operation is important. It is well known that, at low-speed, the saliency of these machines can be exploited for sensorless control down to stand-still through high-frequency (HF) signal injection. Nevertheless, the use of a separate HF model makes more complex the integration with the fundamental model valid at higher speeds. In this paper, an observability analysis is presented, leading to a single observer that captures both the fundamental and high-frequency characteristics of the machine. This leads to the proposal of a single observer, based on the extended Kalman filter algorithm, that is able to merge the saliency information obtained through HF injection and the fundamental information from the back-EMF of the machine. This strategy maximizes the utilization of the available rotor position information, minimizing the amount of HF signal injection required. Hence, leading to increased efficiency and reduced acoustic HF noise while achieving smooth transitions between low-speed and high-speed operation regions.