it got access to two of those miniature oscilloscopes and a Tektronix 2246 Oscilloscope. i have been watching videos on folks fixing their class D amps. when they are testing things i always see them using a single probe. i know the other probe is grounded but to where i am unsure. is this an 'it depends' sort of question or is there sure fire place to ground the 'other' probe? also is 100MHz enough?