What would be the optimal condition if one were to minimize the potential impact that processor usage might have? The random crackling issue appears with max buffers set and MC and chrome the only programs running on a fairly powerful 4 core i7 laptop.
My experience is that it's very audio device specific. I have some sound cards that never experience crackle when being fed from the WDM even with prolonged periods of 100% CPU utilization, and some that experience crackle with even short spikes in CPU usage. I've had two different devices plugged into the same computer, same instance of mediacenter, etc. One will crackle when using the WDM, the other will not.
So I don't think it's necessarily a function of the PC/CPU, but more of a function of the sound hardware/drivers and how MC interacts with them in exclusive output modes.
For example, my Asus Xonar ST (in a new i7 based PC) experiences crackle with the WDM driver regardless of buffer settings (some are better than others, but no combination of settings totally eliminates the crackle). When my sound output to the ST is ASIO, I get less crackle than when it's WASAPI, but in either case I still get some crackle when using the WDM driver. There are specific computer tasks I can perform that always cause crackle regardless of buffer settings.
On the same computer an Asus Xonar U7 (which is an external USB interface), cannot be made to crackle with the WDM driver unless the buffers are set to minimum. Plugging the U7 into an i5, I still cannot get it to crackle with WDM.
My Steinberg UR824 doesn't crackle with the WDM even when the PC it's attached to is running Prime95 on all cores.
I could provide 2 or 3 other examples of interfaces that exhibit consistent behavior; the issue seems to be more audio device driven than computer driven. My general findings are that external interfaces generally do a better job than internal cards (but not always), and Asus has terrible driver support.
