Michael_13,
Well, yes, but because you have two speakers connected to the same terminal, the impedance will be lower so more current will flow to the two speakers. The actual volume increase of running a second speaker from the same terminal will be 3 dB. So, in effect, the surround amp driving those two speakers will be called upon to deliver more "power" to a lowered impedance.
If your manual recommends doing it, then presumably the amp will handle the lowered impedance in the surround channels.
Regards
