But DB25 is still very standard, thanks to all kinds of legacy serial communications hardware still in use. Those used mainly DB-9 and DB-25 connectors.

Yep, that's the TASCAM [1] audio connector which is DB-25 and super common in the audio world. Traditional audio uses AES [2] using either XLR or BNC connectors and only carries two audio channels. The TASCAM cable carries far more channels and, if using digital AES, there is no downside since it either works or doesn't.

[1] https://en.wikipedia.org/wiki/Tascam_Digital_Interface [2] https://en.wikipedia.org/wiki/AES3

Indeed, DB25 is all over pro audio still. It's mechanically fragile compared to elco (or whatever other multipin) or just using a lot of XLR... but it's easy to get off-the-rack or custom DB25 audio cabling.

Well if you use proper old school Metal Shells, shrink wrap the connections and screw them down DB25 can be robust.

DSubs are robust when they are connected, but fragile in applications that require frequent reconnections.

There are vast quality differences in D-Sub connectors. Industrial-spec ones are quite durable, although of course they still have the robustness issue of relatively thin pins that can be bent or broken easily by whacking the connector on the edge of a table or something like that. That doesn't tend to happen with e.g. XLR, Speakon, Hartings or Multipin connectors. However, the pin density of these is also quite a bit lower...

In my experience the higher-spec DSubs are actually more prone to broken pins. The connector is actually meant as cable harness connector for aerospace-ish applications, the whole concept of dsub shells and using it for external cables is largely an IT industry invention that happened few decades after introduction of the connector itself. Micro ribbon (ie. “Centronics”, “Telco connector” and what not) is actually meant for repeated imprecise insertions and has comparable pin density and electrical specification, but thickness of its shell is at the edge of what is practical for various EuroCard-derived backplane systems (which includes PC cases) and thus DSub won.

Ah I see what you mean

It had two DB25 connectors. That's an old analog mixer from 2004. The Mackie webpage doesn't even list products that old.

Of course, their current digital mixers don't have any D-shell connectors.

Well, it's still around, that's for sure...

https://apogeedigital.com/products/symphony-io/configuration...

I mean, I can't afford $5K for that, but it's there.

This is an extremely common and widely used standard for analog and digital connections for pro audio. I just wired in a bunch of DB25 gear last week. For low end / mid range digital stuff it is more common to see ADAT optical digital vs DB25