I reenabled the onboard audio just to see what effect that would have, if any... btw the Realtek HD Audio options mentioned above only apply to that, which is what I figured anyway. Once it was reenabled another option appeared (which I'd read about in the board's manual, finally got to it online) for selecting HD for the FP audio, which I did since I'm using the HD connector on the FP cable. (If I disable the onboard audio, all other subsets of audio options disappear from Setup since they're no longer relevant and I don't get to select any options for FP audio at all.)
Nevertheless, the only difference after the reboot/reset was that when I plugged the phones into either the front or rear onboard audio jacks, the onboard audio software program opened to inform me that I'd plugged something in and wanted to confirm it was headphones since that was the jack I had used. I confirmed that it was but all of that didn't disable the speakers and give me sound from the 'phones via either jack. The only sound from the headphones came when it was plugged into something controlled by the sound card, which the FP isn't. And even when it is plugged into the card instead of the board, the FP jack still doesn't work. So maybe the FP only works if onboard audio is enabled and NOT superseded in any way by an installed sound card, or if the card and the motherboard are somehow sharing the connection provided by the FP audio cable. (That seems to be the point of the connection mentioned in the card's manual altho' for the life of me I can't see how to make that happen since the FP cable doesn't seem designed for it and I can't find something that is.)
The audio card's rear 'phone jack is shared with one of the surround sound speaker jacks, which of course already has a speaker jack in it. I took the speaker jacks out and put the 'phones in instead and did get sound from them, but of course I wouldn't be using that jack for them anyway since the speakers are going to stay connected 100% of the time and they provide a headphone jack to use in that case.
Anyway - onboard audio once again disabled, FP audio cable plugged back into the motherboard where it was when I started, audio via card and speakers sounds great and the card's software program seems to be working fine to manage them. Dedicated 'phone jack on speaker control doodad works fine and is convenient enough to substitute for FP jack, so it's not like I'm *missing* a feature I really need, lol.
The only thing that still puzzles me is that bit from the card's manual about plugging one end of the FP audio cable into the card, and one into the motherboard. I still can't figure out what the heck that means since there are only two "ends" to the cable and one of them surely needs to be plugged into the front panel, while the other doesn't have two HD connectors to split between board and card and I can't find anything that would make that possible.
I may still go back to Asus and see if there's any additional documentation for the board and/or card that clarifies things, if only for my own peace of mind.
