SoftAmp PSA is a virtual-analog guitar pre-amp that combines a noise gate and compressor, drawing inspiration from classic guitar equipment renowned for its distinctive sound. It features five unique distortion stages, with the first three based on op-amps combined with zener diodes, while the last two rely on overdriven op-amps delivering rich saturation. These stages are complemented by a tone shaping section, speaker simulation, and output level control, each contributing to the authentic tonal character. The design focuses on nonlinear filtering, which adjusts output based on both frequency and signal amplitude, resulting in a highly accurate digital emulation of analog distortion.

The unit offers advanced tone-shaping options with two dedicated controls for the speaker simulator, allowing users to customize the tonal shape and frequency rolloff or bypass the simulation entirely for external impulse responses. Additional features include asymmetric clipping, which introduces even harmonics by unbalancing diode voltages in early distortion stages, and a soft-clip mode that softens the transition into distortion for smoother note decay and less harsh overdrive. Visual clipping indicators provide real-time feedback on which stages are saturating, enabling precise gain structure adjustments to shape the sound.

Integrated into the signal chain are the PSI Denoiser noise gate and Squeezo Range compressor, designed to enhance clarity and dynamics. The noise gate features a convenient auto-learn function to quickly adapt to the ambient noise level, ensuring clean signal gating without manual tweaking. The compressor operates just before the pre-amp, offering a musical and nonlinear compression effect that dynamically responds to the input signal. This combination results in a highly expressive and controlled guitar tone ideal for studio and live use.