New sound difficulty

[MR ZenWiz]

I just upgraded my main desktop hardware to a Gen4 i7 with an ASRock
Z97 Pro4 m/b (and a heftier power supply).

>From the first boot, I can't use the analog audio (speaker output on
the back of the m/b).  I comes out slow, repeating and muffled with
static.

If I use the HDMI monitor headphone jack, it's fine.

I have Alsa installed and I thought I had PulseAudio defeated, but it
seems to be running anyway.  I don't believe that's the problem, but
the on-board sound is unusable as is.

Any suggestions for what it might be?  It's really annoying not to be
able to use the sound output on the m/b - one of the reasons I
upgraded.

TIA.

MR