I'm having a similar problem here with extended usage of the new audio driver.
Watching three 45-minute documentaries nose-to-tail in gkreidl's KODI 15.2 started off OK, but the sound on the third documentary started to rhythmically crackle and 'fuzz' around the 2-hour total playtime mark with the audio slowly disappearing behind the noise over the course of a couple of minutes until a loud click was emitted followed by complete silence.
I tried watching three 45-minute episodes of another documentary series the following day and exactly the same thing happened after approximately the same total playback time, so it appears to be a repeatable problem. These are locally encoded files that play back fine in KODI on a Win10 PC, so the files are of known integrity.
It seems to be an application-agnostic problem as I've just been listening to a streaming radio station on the TuneIn website via Chromium 48 web browser and the same thing has happened again after roughly 2 hours of continuous listening.
No amount of switching audio modes or opening and closing other programs that use audio fix it. Only a Raspbian reboot brings it back to life. Nothing odd to see in any log files I'm afraid.
If there's anything you'd like me to try at this end, just give me a shout as I'm happy to make any configuration changes or test any potential bugfixes you'd like to throw my way. I'm probably as keen as you are to see this working 100% due to the night-and-day difference in quality it offers over the old driver.