Notice that the above mentioned poster returned the amp because he read audible sound. The A50+ makes use of a special TI amp chip (TPA3116) but I doubt which was the reason for the sounds since the TPA3116 can evaluate very perfectly. As famous I never hear audible sounds https://finn5jym5.digiblogbox.com/60593807/helping-the-others-realize-the-advantages-of-wood-engraving