To clarify my hardware question, I am looking for a fully alsa-supported
device supporting reliable digital input and output using s/pdif, aes/ebu or
adat (optical or coaxial). S/pdif is most likely what I'll be using.
Connectivity to laptop computers id desirable but not indispensable.
The Core Sound Pdaudiocf (with a PCMCIA adapter) is reputedly good, but it
supports input only - no output.
Another option would be one of the M-Audio cards/devices, provided that Alsa
supports the s/pdif interface.