Note that the above mentioned poster returned the amp because he read audible noise. The A50+ uses a unique TI amp chip (TPA3116) but I doubt that was the cause of the sounds since the TPA3116 can evaluate pretty properly. As pointed out I will not listen to audible https://fernandoey1qd.mdkblog.com/41997654/a-simple-key-for-wood-engraving-unveiled