Used BOSS GP-20 Effect Processor

The used BOSS GP-20 Amp Factory Guitar Effects Processor is in excellent condition and delivers authentic COSM-modeled amp tones with dual amp modeling, 22 amp types, and built-in speaker simulation. Featuring 44 programmable patches, stereo outputs, and intuitive knob-based controls, the GP-20 offers rich, dynamic sound shaping for both stage and studio use. Rugged and reliable, it’s ideal for guitarists seeking versatile tone options in a compact, pedalboard-friendly package.