Bench validation of surface electromyography (sEMG) front ends is often limited by variability among human subjects and experimental logistics. This work presents a low-cost and reproducible sEMG test bench capable of generating analog waveforms representative of upper-limb activity for rapid evaluation of acquisition hardware. A Raspberry Pi streams either synthetic or database-based signals through hardware PWM (≥62.5 kHz). A two-stage low-pass filter, single-supply buffer, and resistor divider reconstruct the PWM into a stable analog output with millivolt-level amplitude and impedance compatible with typical biopotential inputs. The bench was characterized in the time and frequency domains across the sEMG band (≈20–500 Hz) to quantify residual ripple, baseline stability, and interoperability with oscilloscopes and OpenBCI inputs. The platform enables repeatable testing of gain, filtering, saturation margins, and common-mode rejection without involving human participants, reducing setup time and experimental variability. Compared with DAC- or FPGA-based solutions, the proposed design minimizes hardware complexity and cost while maintaining timing stability sufficient for sEMG bandwidths. Design files and scripts are provided to facilitate replication and educational use. Overall, the bench serves as a practical and accessible tool for early-stage prototyping, comparative evaluation of acquisition chains, and teaching laboratories in biosignal instrumentation.