By the way, could you please provide some hints on how to avoid inter-sample overs? Does it require a special DAC or other hardware / software..? Or do I stray too much from the main topic?
Not sure if it’s ontopic.. it might be .
Avoiding them is a complex question. They basically happen at the edge of the spectrum where on high impulses ringing effects become evident. Typically this happens when clipping. Avoiding clipping works well for that. Next to that it’s a property of the DAC’s reconstruction filter and/or upsampling filter. Note that in principal, inter sample overs are not really “wrong” by itself. They make sure that the signal is properly band limited. They are an issue if they make the DAC voltage go against the voltage rails, adding more clipping artifacts. That is why lowering the maximum amplitude by a bit might help smooth those issues a bit. So if you have a DAC prone to this issue: do not set it to max voltage, and/or use an external upsampler that appears to have less issues.