sound problems

So, I noticed a problem with my Topping A50S: when using a 4,4mm-to-3,5mm adapter in the balanced jack, my A50S shuts down with a loud crackling sound at high volume when playing songs dominant in the treble range. I am using it with a FiiO k3 DAC and Beyerdymic DT1990 Pro headphones. Has...

hi im having slightly a sound problem with my teac 101da sometimes the sound will become harsh and then would come and go by itself. now i did send it back to the retailer and they tested it out and everything was fine and they sent it back, i bought it so i can watch movies and listen to my...