It's most likely a Windows 10 fault. Hearing crackling sounds is typically the result of "buffer underuns" and I know the Windows audio stack since Vista is really keen on making crap like that happen all the time.

try changing pci latency in the bios (increase)

It's no bug, it's a feature.

Davros wrote:

try changing pci latency in the bios (increase)

Unfortunately there's no such option in the BIOS. Enabling/disabling other performance tweaks I found there did not help at all.
I've tried disabling in device manager all the network devices, all USB devices (I have PS/2 mouse and keyboard) and the graphics card (switching to Windows default driver) - did not help.
Then I changed the "Minimal Processor State" value in power settings from 5% to 100%. That seemed to help a bit but did not solve the problem.
Changing the Winamp buffer length from 2s to 8s also reduced the amount of clicks, to almost an acceptable level. Not really helpful, because Winamp works fine with DirectSound output (which is the default) or with ASIO plugin.

Then I remembered the Meltdown/Spectre patches. I know I had them installed. I found the way to disable them in registry.

Initially I thought it did not help either. The Windows startup sound was distorted as usual. But after few minutes, I realized the clicks are gone.

It seems the Meltdown mitigation is not the real cause. Whatever it is, the problem is solved by selecting "Wave Out 2/3" as the default output device in Windows mixer settings. Before, the default device was Master Mixer. Both are "kX 10k1 Audio" devices (there's also Wave Out 4/5, and 6/7, whatever those mean).

To sum up, the initial problem (clicks with integrated audio) was solved by:

- installing a Sound Blaster (SB0220, although I'm waiting for SB0090)
- disabling integrated sound in BIOS - just to be sure
- installing kX drivers and Win10 patch
- selecting Wave Out 2/3 as the default output device.

I just replaced SB Live with Audigy. Same drivers, without reinstallation.
No clicks so far.