Because the speakers are in parallel the impedance drops which increases power. Be careful your impedance doesn't drop too low because of that especially at high volumes.
Will using bothA and B spkr out half amps power?
I have an NAD int amp powering Usher speakers. Im experiementing with a old Paradign sub which is passive so I have it hooked up to the B speaker outputs of the amp. When I am running both A and B, does it mean I am running less power to my Ushers? Seems to me it would be half power. BTW-the sound quality without the sub in the system is better, but Im curious about how the power is divided when A and B are engaged. Thanks.