A management server controls, by use of a first database, a first audio client system that includes a first speaker and a second speaker. The first database includes a first standard characteristic impedance, which is obtained by application of statistical processing to a first characteristic impedance of the first speaker and a second characteristic impedance of the second speaker. The management server acquires a new characteristic impedance of the first speaker, compares the new first characteristic impedance with the first standard characteristic impedance, to determine a condition of the first speaker, based on a result of the comparison. The management server updates, based on the condition of the first speaker, the first standard characteristic impedance of the first database, using the new first characteristic impedance.