The Radial Highline Stereo is a passive stereo line isolator designed for guitarists using amplifier simulators and modelers. This compact DI box converts unbalanced line signals to balanced signals without compromising volume or tonal quality. Featuring high-quality Jensen 1:1 transformers, it effectively isolates signals, protects against phantom power, eliminates ground loops, and maintains complete signal integrity. The unit measures 108 mm in width, 70 mm in depth, and 44 mm in height, making it suitable for pedalboards and professional audio setups. Key functionality includes stereo inputs and outputs for routing flexibility, allowing users to drive multiple rigs, split signals, or convert stereo XLR signals to mono. The sum function enables seamless mixing of stereo sources to mono through the input and thru connections, which operate as passive mixers. This feature helps conserve mixer channels while maintaining stereo thru outputs. A ground-lift switch provides an effective solution for removing unwanted hum and noise from audio lines. Constructed with professional-grade components and finished in black, the Highline Stereo ensures clean, protected signal transmission from input to output. It serves as a reliable interface between amplifier simulators and mixing consoles, stage monitors, or in-ear systems. The device supports both studio and live performance applications, offering enhanced signal management capabilities for modern guitar rigs. With its robust build quality and precise audio processing, this line isolator delivers consistent performance in demanding audio environments. The Radial Highline Stereo represents a practical solution for musicians seeking to maintain signal purity while expanding their routing options in complex audio setups.