Neptune uses advanced digital signal processing to enhance the listening experience on Apple EarPods and AirPods (1st and 2nd Generation). It corrects both frequency and phase responses, ensuring audio playback that is balanced and true to the source. By applying a specialized crossfeed algorithm, Neptune simulates the natural sound of loudspeakers, providing a more immersive and comfortable listening environment that reduces listener fatigue.

Standard headphone listening often results in an exaggerated stereo separation and an unnatural soundstage because each ear receives isolated audio channels directly. Neptune addresses this by mimicking how sound behaves with speakers, where low and mid frequencies from both channels blend with slight delays between ears. This approach enhances spatial realism and creates a more cohesive and natural stereo image, making headphone audio feel less artificial and more akin to real-world listening.

Neptune offers several features designed to optimize audio quality and usability, including frequency and phase response correction, FIR filters that reduce ringing, and a linear phase mode for consistent sound reproduction. It also supports zero latency mode and an adapter compensation mode for various headphone connections. Additionally, Neptune is designed to operate efficiently with low CPU usage, making it suitable for real-time audio applications without compromising system performance.