The driver can start the buffers synchronously, so you
have
sample-synchronous output. To have jack working with multiple cards, you
can either use alsa magic to combine the cards, or use alsa_out (with
disabled resampling).
Will try that with a couple of hammerfall 9632 we have in
the lab before
buying the (two) AES-32.
Any recommended documentation or advice?
The RME cards are easy to set up: Just connect the internal sync port
using the cable that came with the cards and select "Internal" as sync
source on the slave card.