\ They can provide relatively inexpensive and foolproof locking banana plugs that make very solid connections and never risk coming loose or damaging speaker terminals as some do by using a pipe wrench to try and tighten spade lug connections.
I agree with the banana plugs. I know why people use wrenches with cheater bars, monkey wrenches, etc, on spade lugs - because they come loose incessantly otherwise. To get a solid connection, you have to put enough torque on it to stretch the metal of the post slightly. Otherwise it gets loose. The larger the diameter of the post, the more torque it requires. Of course the lugs themselves are usually massively oversized for the terminal, so many times they won't fit properly anyway.
When checking out other people's system problems, I perpetually find them loose, with one leg stuck through the hole and the other free, and of course, the terminals damaged or twisted off completely from the use of the aforementioned cheater bar. Even sticking the bare stripped wire through the hole is better - except for the fact that the grossly oversize wire won't go through the hole. I long since gave up trying to talk people into replacing their 8-gauge "magic speaker wire" with 75 cents worth of zip cord. Apparently the smaller diameter won't hold enough magic.
The only way to resolve it (other than just use banana plugs like a grownup) it to bend the arms of the spade lug out of plane. A small bend in each leg will permit a bit of spring tension to provide enough give in the system to remain reasonably tight without having to crank down on it like it's a NASCAR lug nut.
Brett