Notice that the above poster returned the amp mainly because he heard audible sounds. The A50+ works by using a different TI amp chip (TPA3116) but I question that was the cause of the sound since the TPA3116 can measure very effectively. As famous I never listen to audible sounds https://vymaps.com/US/Displays-Holders-VN47468/?id_new=1662a5af81416c2689d94e902b8d12d6