If you examine a detailed stk412-400 circuit diagram that includes the circuitry, you will notice:
Most implementations require a dual-rail supply (e.g., +VCCpositive cap V sub cap C cap C end-sub GNDcap G cap N cap D −VCCnegative cap V sub cap C cap C end-sub stk412-400 circuit diagram
Less than 0.08% at rated continuous output (1kHz fundamental). If you examine a detailed stk412-400 circuit diagram
. The moment a deep transient peak or bass note demands higher output voltage swing, the internal gate controllers shift the path to the ±VHplus or minus cap V sub cap H power rails. Critical Circuit Diagram Connections & Pin Functionality stk412-400 circuit diagram