As far I understood Smsl changed an OPamp and the software (after Amir's test) Amir's test was obviously with an error free device.
It's a conclusion I would not draw.
The FW was flawed from the start and is the only issue.
The opamp change isn't an audible issue at all and may have been the 'cheaper one' from the start of sales just not in the pre-production sample.
That sample was plagued with instability issues and was distortion related but Amir checked both channels at the same time so the issue may have been there all along.
Masking of 3rd harmonics is about -60dB at normal listening levels. The louder one plays masking gets even better.
The issue is down -80dB so well below masking levels using 'tones'.
With music I doubt this is even audible at all and is why no one hears this issue (also not Amir because he was not listening for it).
The issue exists, it should not be there. It will be 'fixed' in future versions for sure.
It is very measurable but below audible levels using music anyway.
No one, in any threads reported poor sound quality so no-one seems to have noticed.
Of course there are the golden ears that don't like the brand and stated they hated the sound and they will claim they heard it.