Quote:
Originally posted by bigmac:
An audio signal on the interconnects will vary from 0V to something like +2V.


This can be true of a single-ended gain stage or DAC output within a piece of equipment, but no RCA jack should ever output a DC voltage. To amplify previous comments (no pun intended), a DC voltage is defined in linear systems theory as the constant or non-sinusoidal component in an FFT decomposition of a signal. A signal which varies between 0 and +2 volts has a +1 volt DC offset; whatever sinusoidal components (sounds) are carried through such a signal are the AC components.

Quote:
Originally posted by bigmac:
You can disconnect your left ground wire, tie it into the right ground, and your speakers will still work.


This is not related to whether the signal is 0 to X volts or -X/2 to +X/2 volts. In either case, the ground terminal (interconnect or speaker) serves as the constant voltage reference. Moreover, for balanced amplifier topologies such as the Pass X series, you can't do this, because the "black" and "red" terminal voltages vary in equal and opposite directions.

Quote:
Originally posted by soundhound:
these are the generally accepted definitions of AC and DC, except in some parts of West Los Angeles.


Hehe... Among the silliest things I've ever seen was a heated debate (after many, MANY drinks) between two electrical engineers arguing about whether AC or DC was the proper indication of "which side of the fence" they were on. It turns out that, after five minutes or so of banter, to both's surprise, they were on different sides of said fence.