preamp inverts polarity

“why single ended amps best emulate the character of the medium sound travels through”

This is very intriguing. Does this have to do with how the electrons move to create voltage to drive the speakers or something else? Hard to connect the dots.

Hey, I’m going to clunk your heads together. You do not (rpt not) obtain a vacuum by compressing air. You suck the air out of the container to produce a vacuum. A vacuum is measured by no. of air molecules per unit volume. A perfect vacuum would have no (as in zero) molecules at all. Obviously, a tremendous mass will compress air a lot but not (rpt not) completely, which is why air shock absorbers work even for very massive commercial jetliners. PV equals RT. The number of gas molecules in the container remains constant. Hardly a vacuum. In fact there are MORE molecules per unit volume when the air is compressed. A lot more.

geoff, read their posts again...they said “ decompress” air not compress. Either way, you’re correct about how vacuum is obtained. 
I’m still stuck on that single ended amp remark...😁

@kalali

Just to be clear here, Push-Pull amps can be class A and also all triode. The 'air is single-ended' thing is a bit sketchy and also a bit of a red herring, since air has nothing to do with how amplifiers operate.