FWIW - it appears that 1.9.3 introduced a few regressions for HDA hardware compared with 1.9.2 - ie with 1.9.2 the hang after second sound was gone, with 1.9.3 it's back.
I think I understand why this has happened, and have a couple of ideas on how to fix the problem.
Please grab http://download.smedley.info/uniaud32-1.9.3-testfixes.zip and try each fix inside the zip file (contained within test1 and test2 directories) - and let me know which (if either) works best.
Thanks!