I remember reading about this question over a year ago and my feeble mind can't remember what setup would be best. I am powering our bands monitors with two 8 ohm speakers and a soundtech ps802 amp. Since the amp will only bridge down to 8 ohms minimum, I need to use either one side of the amp for both speakers, or one speaker for each amp channel. Each channel delivers 400 watts at 4 ohms. In the one channel two speaker arrangement, each speaker will see 200 watts and the amp will be delivering maximum available power. In the one speaker for each channel arrangement, the amp will be delivering roughly 285 watts to each speaker. A slight improvement in headroom, but the amp will be working harder at 8 ohms. My choice would be to go with headroom over amp operating efficiency? Anyone care to comment?