A rapid signal processing technique with real-time visualization is essential for non-destructive testing, particularly in scanning acoustic microscopy (SAM) applications. Recent advancements leverage graphics processing unit (GPU) for parallel processing, significantly improving imaging speed and responsiveness. However, the majority of experiments use a single transducer under standard conditions. In this study, we employed GPU-based signal processing for four transducers to enable real-time processing of acoustic images. The average processing time for a four-channel C-scan image of a Spartan 6 chip sample was approximately 5.7 seconds (s), achieving a display speed of 96.49 frames per second (FPS) with sample parameters of 960 (axial) × 550 (pixels) × 550 (pixels) at an average pulse repetition rate of 11 kHz. Our results demonstrate that GPU-based signal processing with multi-channel not only enhances SAM system performance but also provides a more comprehensive and accurate analysis for non-destructive evaluations.