The woofer is a "high 4 ohms" woofer, DC resistance about 3.95 ohms. The switch introduces 1.05 ohms of series resistance in the form of nineteen 20-ohm, 20-watt resistors in parallel, which results in a "low 8 ohms" DC resistance of 5.0 ohms. The switchable 1.05 ohms is actually in series...