Whichever kernel-power is in devel at any given time, with, I believe, nearly stock if not completely stock swap settings and no overclock

From America to Russia.

That said, I have indeed had voice quality degradation, some calls do degrade to un-usable-ness, sometimes immediately, sometimes over a long time and only after a while on the line. Sometimes it's perfectly good though. Typically I can comfortably talk for an hour or two with just a couple of retries.

So far I've been chalking any issues up to internet connection issues here and there, what with it being an America to Russia call. Plus from what I hear skype can just be problematic every once in a while. *Shrug*