Yeah, series and parallel are supposed to have different tones... I don't have my amp books here so I can't tell which are. But, if you think in safety the parallel it's better. If a speaker from a 2x12 cabinet blows up and they are wired parallel mode the amp will be running with with and unmached impedance. That'll let you time to go an turn it off. If the speakers are wire in series that'll be a dead amp and that it isn't good at all!!!