Open the bottom and check the flimsy sand resistor in series with the input, being paralleled by a 220uF lytic.
These are the things that would break over time and cause the speakers to distort prematurely, with a domino effect of getting the triac clamp that is activated by ionization detection to kick in and shut down the speakers.
This is a protection mechanism that is very hard on solid state amps so user-beware.
There's another thing called a thermister next to the resistor and cap that supposedly increases in resistance when the speaker is overdriven. But that thing does more harm than good IMO.
Check out other 988 989 postings on the forums on how to upgrade and watch for failure.
These are the things that would break over time and cause the speakers to distort prematurely, with a domino effect of getting the triac clamp that is activated by ionization detection to kick in and shut down the speakers.
This is a protection mechanism that is very hard on solid state amps so user-beware.
There's another thing called a thermister next to the resistor and cap that supposedly increases in resistance when the speaker is overdriven. But that thing does more harm than good IMO.
Check out other 988 989 postings on the forums on how to upgrade and watch for failure.