Not everyone will agree, but I've tapped off the binding posts of my main speakers for a speaker level run to my subs. Never heard an issue using this method, but in a perfect world there are adapters that are designed to make barrier strips a bit more versatile and user friendly. Or in a pinch, you could simply strip the ends of a stranded #14 or #16 gauge wire and share the terminal with the spade connectors for you mains. You don't need a "garden hose" wire for a powered sub.