Last Fault A 4098 OVER VOLTAGE

[AlexS]

My logic for why it is not the incoming mains is as follows.

I have dual mono plugged into the same double socket, they are affected independently, where as the mains voltage must be the same going into both.
It happens a lot with specific SAM settings, but not with other settings.
I have monitored my mains, and they were fine when it happend.
It's worse when I play loud and with deep bass music.
It's not my amps, they leant me a 440 to try, it happend within a few mins of powering on with my 'bad SAM' settings.

All of the above tells me it's some sort of firmware / maths / DSP issue, something is being too clever internally.

If they tell you it's your mains again challenge them to provide a mains conditioner or voltage logger for your mains to prove it, it would be useful diagnostics for them.

If you are using SAM change it's % setting 1% and see if it gets better or worse.

This feels like a rounding error bug to me, so any tiny change in SAM % will change the calculation.

You have interesting points. The strongest argument is that with the dual mono setup, you get the error for the individual units. However, as you've noted, if the condition depends on the internal state of the amp, the left and right channels process different data at any given point of time.
My main reason for suspecting issues with the mains is that for me, the problem manifests itself more frequently in the summer, and during thunderstorms. What's more, it usually happens after 11, when the voltage may be bumped up by my electric company, due to lowering demand related to Air Conditioning. All in all, enough evidence to prove that the problem requires some predictable external conditions (SAM may be exacerbating the problem, and that's why I've always stayed away from it).

As for @Axel's comment about not worrying it, there is definitely a large degree of wisdom in it. And yet I can't stand these sudden interruptions (they give me a start). If I can spend under $1000, and solve it once and for all, I will.