Components in electronic equipment degrade and fails, what is really your problem would require a skilled person to test and investigate usually.
You do not supply enough info here for anyone to tell you a straight answer.
I have a Xin SuperMacro3, used and abused over 12 years approaching, have had problems with distorted sound a couple of times.
It was assembled with sockets, not soldered, possible to reroute signals/upgrade by the user, and after being carried in moist environments (sweaty pockets / Asian holidays!) I suspect contacts had been oxidized and made signals break up.
Twice now over 12 years I have dismantled the amplifier completely, cleaning everything in WD40, and reassembling the unit.
After that there is no more distortion!
If you yourself cannot analyze your unit, ship it back or bring it to a local electronic workshop for someone to try to find out.
