On Mon, Nov 11, 2019 at 12:26 PM <lacuna_@gmx.net> wrote:
 I'd like to run up to nine soundcards with Jack.

Eight times Expert Sleepers ES-8 via USB
and one RME Madi HDSPe card on a PCIe slot.

In Linux at 96 kilobauds.

I read here
about clocking issues as each card is run by it's own clock.

Will the asynchronously clocked streams be handled and merged by Jack or is this an ongoing issue?

JACK2 (the one most commonly installed on Linux systems) can't do this by itself (for now)

You would use an instance of zita_a2j to connect each "secondary" card to the JACK server which is using the "master" card. zita_a2j will resample as needed to keep things in sync.

JACK1 can do this by itself because it has zita_a2j built in. However, it is a slightly older version of zita_a2j and I discovered recently that it doesn't handle xruns as well as the current zita_a2j.

I imagine, if I'd feed analog outputs of one card into the analog inputs of another, this wouldn't be ideal.
But I am wondering if Jack is handling the asynchronous streams in the software-domain without glitches ect. ?

With a powerful computer is the latency going to rise absurdly high? Any experience with this?

Number of cards has nothing to do with latency directly. "Servicing" each card will consume some of the time available for audio processing. How much is hard to say, but with mid-size buffer sizes, I would not guess that it will be too large.  Since you are not sharing word clock, they will drift and zita_a2j will have to do resampling, which will also consume some CPU cycles.