We've announced OSS v4.0rc2-build 172 for FreeBSD (x86 and amd64) and there are a number of bugs fixed with this version. Kindly try it out and report issues to email@example.com.
Specifically problems with AD198x HD codecs is fixed
Issues with ATI HDaudio controller fixed
Issues with STAC92xx codecs fixed
Playback and recording works pretty well. SPDIF hasn't been fully tested.