Abstract: Apparatus and method for selecting an optimum gain for an amplifier used to amplify readback signals transduced from a magnetic recording disc in a disc drive. The amplifier is provided with a first value of gain, which is used to amplify a readback signal to generate an amplified readback signal. The amplified readback signal is in turn applied to an automatic gain control circuit comprising a variable gain amplifier. The variable gain amplifier applies a variable gain from a selected range to the amplified readback signal to maintain an amplitude of an output signal provided by the automatic gain control circuit at a nominal amplitude. The acceptability of the first value of gain for subsequent use by the amplifier is determined in relation to a magnitude of the variable gain applied by the variable gain amplifier.