Polarity Conundrum

Yes, it’s that simple, assuming two things:

1) Most importantly, this assumes that the speakers are passive, e.g. they do not include built-in amplification, and that powered subwoofers are not connected to the amp outputs. In either of those cases it might not be safe to connect the + output of the amp to the - input terminal of the speaker or sub.

2) It assumes that the polarities of your source components conform to the usual USA convention of pin 2 positive and pin 3 negative in the case of XLR outputs, or that the source components are not polarity inverting in the case of RCA outputs. Otherwise interchanging + and - at the amp outputs would be introducing a polarity inversion, rather than correcting for one, since having two polarity inversions in the signal path results in correct overall polarity.

Finally, some will argue that whether or not you interchange the + and - connections at the amp outputs is unlikely to have much if any audible significance. And IMO they would be correct in the case of many and probably most recordings, but not all recordings.

Regards,
-- Al

Its reasonable to think you want your system to play with the correct polarity but not all recording are mixed with the correct polarity.  So it is hard to know what you are listening too.  According to this site 92% of CDs are inverted polarity.  I guess you can look at their list and swap your speaker cables for the various albums before you play it.    Or you can not worry about it and enjoy the music.

http://audiogeorge.com/the-polarity-list/  

Thanks for the responses....the one source that I'll also have connected via XLRs has the US-version polarity arrangement, so that helps rather than hurts the situation. My speakers are passive and I am using a sub, but it is connected directly to preamp outputs on the LS-15. My head tells me to reverse polarity at the amp outputs, but my gut says to wire as normal and see how that sounds first. It doesn't help that I haven't had the speakers I'm using (Vandersteen 3As) very long, so discerning any subtle differences, if any, may be difficult.

More options:

https://www.amazon.com/dp/B0002J1JN6/ref=psdc_11973421_t2_B000068O4L

https://www.amazon.com/Hosa-GXX-195-XLR3F-XLR3M-Reverser/dp/B000068O4L

I don’t think anyone really knows the actual percentage of CDs that are manufactured or recorded in correct polarity. I’m not sure I even follow the logic for how George Louis arrives at 92%. If it doesn’t make sense it’s not true. Besides, some of the CDs George Louis claims are in reverse polarity in reality sound like they are in correct polarity. There may be many others. 

The obvious best solution is a polarity switch on the preamp. Otherwise one would have to listen to each CD and mark it for polarity. The system polarity can be checked using the XLO Test CD or any Test CD with a track for testing whether the system is in phase or out of phase. But that actually doesn’t help too much since there are presumably a lot of CDs that are in reverse polarity. Nobody knows how many.