Hello, Moderator...
Thanks for timely reply. The case is an Antec Sonata, 10ish yrs old. The front panel jacks plug into the MB. All previous experience w/ sound cards did <not> require re-routing these to a/the sound card. Also, front panel lines are in a bundle, and I don't think that the earphone jack lines can be easily dissected out of the bundle to go somewhere other that the standard jack on the conventional ATX MB. Also/again, the installation guide for the sound card [minimal at best] does not mention this variation. Comments on these "complications" much appreciated. Happy New Year to you.
... robert