Question about polarity-inverting preamps

Many of these amps are single-ended, that is, they have one output signal referenced to ground. In such case, one cannot simply switch signal and ground to reverse polarity. The only way would be to add another stage which ain't the best way. Swapping the speaker leads does it better.

The above have it correct. Conrad Johnson and Blue Circle preamps are out of phase for this reason (less is more) and are among the best.

My moving coil phono stage is out of phase. Since moving coil cartridges have such a low output, adding the additional gain stage to correct the phase would add unnecessary noise to the phono circuit. To correct this I reverse the leads on the tonearm going into the cartridge.

Some preamps (Atma-sphere & Sonic Frontiers to name a few) have phase inverter switches to let you A/B the sound. This is a really nice feature. Happy Tunes!

Is that really "phase inversion" with the Atma & SF preamps, or are those switches really reversing the phase as in polarity?? If so, not exactly the same thing. We had a discussion on this a week ago. Search the other threads.

Those that own those preamps can test it. Play some music with a loud whack of a bass drum or something that makes the woofer on your speakers push out a lot. Then try it again after pressing the switch on your preamp. If it is inverting the phase 180 degrees, the woofer will now be sucked in a lot, instead of pushed out.

Here's some food for thought... in a single ended system the preamp's input signal is configured as a positive and a ground. To process the signal the preamp can only work with the whole wave, both positive and negative. So out of necessity the preamp inverts the incoming positive to generate the missing or negative half. To make the output useful at the single ended connector the processed wave must again become single ended, that is, split. Whether the positive or negative becomes 'the signal' appears to be arbitrary. My uninformed guess as to why the output remains inverted is that the inverter plays a part in the splitting process. Who really knows why?