The present invention relates to a method of selecting a range of gain values (2000) of a gain-bandwidth limited photo-detector circuit (45) for reading data from a record carrier (104). The method comprises: a) finding a first read power by setting a maximum allowable gain value (gmaχ), the first read power being a minimum read power value at which data is readable from the rotating record carrier at a first speed; and b) finding a second read power and a second gain value, by increasing the first read power value and decreasing the maximum allowable gain value. The second read power being the minimum read power value at which data is readable from the rotating record carrier at a second speed. The method is useful for all kinds of photo-detector circuits in optimizing gain values and achieving optimum performance with the optimum number of gain values.