These are tweaks and modifications submitted by individual contributors and not from the Quad factory, and are typically ones that the factory could not do while keeping user costs down. These changes are ones that can be used to make your speakers sound better, in some environments, and possibly at greater expense. These also possibly void your warranty and/or make your speakers more vulnerable to damage.
YOUR SPEAKERS WILL SOUND WONDERFUL WITHOUT DOING ANY OF THIS. But, if you want to squeeze every last bit of performance out then try them. How is that for a disclaimer?