A hearing aid system comprising a first hearing aid device and a mobile device, wherein each of the devices (2,3) comprises a transmit and receive unit for establishing a short range wireless link between the devices (2,3), wherein at least one of the devices (2,3) comprises: a microphone configured to receive an acoustical audio signal, a signal processor configured to process an audio signal based on the acoustical audio signal, and first link quality estimating circuitry configured to determine a phase error of an information packet transmitted from the other device and received by the receive unit in the at least one of the devices and determine a link quality signal based on the phase error, wherein the phase error is determined by averaging the phase error of the multiple samples/bits of the information packet, and the average phase error per information packet is further averaged in between several information packets, and wherein the at least one of the devices (2,3) is configured to transmit the link quality signal to the other device, and the other device is configured to determine the power level of the transmission of the information packet based on the link quality signal via a power controller comprised by the other device, wherein the at least one of the devices (2,3), the first hearing aid device and/or the mobile device, comprise second link quality estimating circuitry, where the second link quality estimating circuitry is configured to determine whether one or more information packets are lost and/or to determine a number of bit errors, and the second link quality estimating circuitry is configured to determine a second link quality signal based on the determined number of lost information packets and/or the determined number of bit errors. a microphone configured to receive an acoustical audio signal, a signal processor configured to process an audio signal based on the acoustical audio signal, and first link quality estimating circuitry configured to determine a phase error of an information packet transmitted from the other device and received by the receive unit in the at least one of the devices and determine a link quality signal based on the phase error, wherein the phase error is determined by averaging the phase error of the multiple samples/bits of the information packet, and the average phase error per information packet is further averaged in between several information packets, and wherein the at least one of the devices (2,3) is configured to transmit the link quality signal to the other device, and the other device is configured to determine the power level of the transmission of the information packet based on the link quality signal via a power controller comprised by the other device, wherein the at least one of the devices (2,3), the first hearing aid device and/or the mobile device, comprise second link quality estimating circuitry, where the second link quality estimating circuitry is configured to determine whether one or more information packets are lost and/or to determine a number of bit errors, and the second link quality estimating circuitry is configured to determine a second link quality signal based on the determined number of lost information packets and/or the determined number of bit errors.