Or, for your convenience, here's the first 2 sentences (emphasis mine):
I assert that this is categorically incorrect.Summing in the analog domain is widely regarded as superior to mixing "in the box." The DSP required to sum individual channels into a stereo pair is prone to clock-based errors and mathematically unrelated signal artifacts, something avoided entirely by mixing down in the analog domain.
The process of summing ITB is, in fact, not prone to clock-based errors - because there is no clocking going on! The summing itself just happens one sample at a time, in what is essentially a non-realtime process. (I could illustrate this more at length - but in short, you don't need a clock to say "sum all samples at time slot 1, now sum all samples at time slot 2, now sum...")
On the other hand, OTB summing does bring your clocking into play. So, quite to the contrary of Black Lion's claims, mixing down in the analog domain does NOT avoid "clock-based errors" - it instead re-introduces them!
Anyways, I know Black Lion gets a lot of respect on this board, and maybe their products are indeed fabulous. But letting their copywriters run wild with some pseudo-science-sounding bullshit isn't doing them any favors.