On Sat, 30 Aug 2014 17:04:56 -0700, "William Sommerwerck"
wrote:

"Cursitor Doom" wrote in message
.. .

I'm not using a resistive probe to measure so additional loading is
scope's intrinsic 1Meg || 20pf.
Still can't believe that little across 8 ohm can cause such mayhem,
though. :-/

Ground problems?

Might be! See my reply to Trevor.