Power supply: DC 919V This circuit is designed to address low output volume from devices when connected to a power amplifier. It provides small signal amplification with a gain of 10 times (20 dB) and offers a convenient front 3.5 mm interface that can be used to connect headphones. Amplifier chip: NE5532 dual opamp Key benefits and features Improves lowlevel audio: increases the signal from a device before it reaches the power amplifier, helping to achieve a clearer and louder output. Clear gain specification: 10x gain (20 dB) to boost small audio signals effectively. Headphone compatibility: front 3.5 mm interface allows direct connection to headphones for monitoring or listening. Reliable audio component: uses a dual opamp NE5532, a wellregarded device for audio applications. Flexible power range: operates from a DC supply in the 9 to 19 V range, accommodating different power options. Applications and use scenarios Scenario 1: You have a portable audio source with output too quiet for your power amplifier. Use this circuit between the source and the amplifier to achieve a stronger final sound without replacing existing equipment. Scenario 2: DIY audio project or testing setup where a simple preamplification stage is needed. The NE5532 dual opamp provides a straightforward solution for boosting small signals and enabling headphone monitoring via the 3.5 mm jack. Scenario 3: listening and debugging. Connect headphones to the front 3.5 mm interface to verify signal levels and behavior before integrating the circuit into a broader audio chain.