testpilot
For example, there are servo-controlled woofer systems that require the amplifier output to have the same polarity as the preamplifier output. Major problems can follow if the two are not in agreement.
Terminals are clearly marked for polarity for the sole purpose to insure that both the Left and Right speakers are wired with the same polarity.That is mistaken. There can be other reasons that it's necessary to maintain polarity.
For example, there are servo-controlled woofer systems that require the amplifier output to have the same polarity as the preamplifier output. Major problems can follow if the two are not in agreement.