I don't know why it doesn't work in the car with 12 volts and in the laboratory with the same 12 volts yes, I have to do some tests.
Good product for the price. Received the amp in 3 weeks. The metal casing is well made. Using an old notebook 16V power supply, the sound is clean after 1 hour of running the amp. The amp runs quite cool judging by touching the internal heatsink. The sound quality is better using the RCA inputs.