If you cannot find the original LAC503P datasheet, test for equivalence with these common parts (using a component tester or oscilloscope):
The LAC503P amplifier is a high-performance audio power amplifier designed to deliver exceptional sound quality with low distortion and high power output. This amplifier has gained a reputation among audiophiles and music enthusiasts for its clear and detailed sound reproduction, making it a popular choice for music lovers who demand the best. lac503p schematic
What is this chip inside (e.g., a specific LG or Samsung soundbar)? If you cannot find the original LAC503P datasheet,