The output attenuators of the DAC1 and the DAC1 USB optimize the signal to noise ratio (SNR) of the interface for maximum performance. They also determine the volume control position at normal listening levels. The output attenuators are factory preset to -20 dB. This setting is required for many active speakers and power amplifiers but may not be optimal for your specific equipment. Please note that the attenuators do not affect the levels at the RCA outputs, which are designed for consumer-level signals.Read more