Repeating a myth on a forum 10,000 times doesn't change it into truth.
Nearly all forum talk about biamping, in the context of passively biampable home speakers and otherwise unused amp channels, is just plain incorrect and confused with other biamping applications not typically found in the home. I often wonder how many of the people who talk about it tried it, and of the few who say they did, how many pushed their system to the limit where biamping, even passive, can make a difference.
The most basic understanding of Ohm's Law is required but if you follow my linked posts all the way back to the first one, it's all explained in lay terms. By the end of that discussion most posters including those bashing passive biamping as a waste of the amp's energy, including one who built his own actively biamped speakers, finally got it.
The most important noise floor is in your head. Always remember to protect your hearing.