@vlio: you would have to investigate the JACK OSS backend, which is supported by only one developer, and even then only intermittently. There are very, very few users of JACK on Linux who use the OSS backend, and quite a few developers who wish that, on some level, it simply did not exist (I am one of them, even though I entirely understand the reasons for its original creation). I very much doubt that your HDA device cannot be made to work with ALSA, and I suggest you focus on that approach, since you will find many, many more people who have tackled similar issues.
Thanks for your comments.
When I have time I will switch to 9.10 (or more probably 10.4 by then) and try once more to make the whole ALSA/PulseAudio thing work, which will probably happen one day but for now I am pretty sure it won’t work correctly (no sound in headphones, things like that).
I know there are very few people using OSS these days, which is why it’s so hard to find solutions to problems with it, but for my part I am quite satisfied with the way it is working (surely better than PulseAudio last time I tried it)