Take the hint that the title of that section is giving us: neither of the options results in an audible improvement and they're there to satisfy the misconceptions of the misinformed/uninformed. Andrew touched on the stamped/cast frame point
here .
On the inputs, you can't "feed" a speaker any more power than it needs at any given instant in time to play at the needed volume level(typically about 1 watt at a comfortably loud average level). The maximum needed on a brief peak is much more, of course, but the capacity of the amplifier's power supply section is the limiting factor, and feeding that same supply through two wires rather than one can't double the max available or increase it in any amount.
