You can switch the polarity at the speakers or the amp, but if you do both it is the same as not doing anything (double negative = positive). :)
I'm not understanding your setup clearly but if your preamp inverts you can invert the speaker or amp leads to correct polarity. If your amp and preamp both invert, again, it's a double negative which would result in the correct absolute polarity.
Your electronics would not sense the inversion and certainly would not correct it automatically. If your preamp has a polarity invert switch, you can correct it that way, but most folks prefer to swap the speaker leads.
But about 50 percent of your recordings are recorded inverted anyway, so whichever way you set it up, it will only be correct half the time. I have a DAC in one of my systems that has a polarity invert feature and it works very well for me. When I think a recording does not sound quite natural, I push the invert button and usually it sounds better inverted. Don't get too hung up on this one thing -- there are plenty of other details to worry about!
I'm not understanding your setup clearly but if your preamp inverts you can invert the speaker or amp leads to correct polarity. If your amp and preamp both invert, again, it's a double negative which would result in the correct absolute polarity.
Your electronics would not sense the inversion and certainly would not correct it automatically. If your preamp has a polarity invert switch, you can correct it that way, but most folks prefer to swap the speaker leads.
But about 50 percent of your recordings are recorded inverted anyway, so whichever way you set it up, it will only be correct half the time. I have a DAC in one of my systems that has a polarity invert feature and it works very well for me. When I think a recording does not sound quite natural, I push the invert button and usually it sounds better inverted. Don't get too hung up on this one thing -- there are plenty of other details to worry about!