Hi, if you turn off the sound system in kde Control Center, and reboot,
is the sound different?
A quick google shows many problems where hdmi exists, and various solutions
From a Suse sound problem discussion:
A possible fix to choppy / skipping sound
The PulseAudio sound server was written to use timer-based audio scheduling instead of the
traditional interrupt-driven approach. This is the approach that is taken by other systems
such as Apples CoreAudio and the Windows Vista audio subsystem and has a number of advantages,
not the least in reduced power consumption, minimization of drop-outs and flexible adjustment
of the latency to the needs of the application. However, timer-based scheduling may expose
issues in some Alsa drivers. To turn timer-based scheduling off, replace the line
load-module module-hal-detect
in /etc/pulse/default.pa by
load-module module-hal-detect tsched=0
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someone had power management impeding audio:
After I went into my CCC and the Overdrive section, I noticed the GPU/RAM was idling at about
35% regular clock speed (to power save). I unlocked overdrive and left it at the default setting.
The GPU/RAM now remain at full speed when idle and I haven't had any audio static for the last couple days.
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someone with an ATI Catalyst solved a sound problem:
Installed ATI Catalyst 9.8, uninstalled OSS, installed alsa again = Crystal clear sound in my
tv HURRAH! It was a Catalyst bug after all, thanks for the bug guys.
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These may not solve your issue directly, but hopefully inspire your efforts!
I reinstall when things don't add up. Minime 2009 was great, just a nice shell
to add only what I wanted. And I kept all the rpms in the cache,
over the years, I've filled up a dvd with rpms to use in a pinch, and there's
nothing like new linux rollouts to keep the pinch supply well stocked.

Cheers