Rudi,
the uniaud api talks direct to the driver (32 bit part), while DART uses the 16 bit part to talk to the 32 bit part. all i can say is that with the uniaud api i have never had a hang in HDA, while using the DART api i had hangs. With the current uniaud driver also those hangs are mostly gone. what i still have with the DART api are sound loops, while with the uniaud api i never have those. i see them mostly with emperoar tv , when i have a not so good connection.
regards
Silvan