Definition: Excessive woofer cone excursion

Gunbei's definition is certainly correct, although perhaps too conservative, as the effect described is "bottoming out" the woofer and is akin to fully extending or compressing the suspension on your car. If you've ever done that you have an idea how bad it is; it would probably be considered abuse by the manufacturer. I had a dealer once tell me that if you can see the woofer moving at all, that's excessive. Perhaps the truth is somewhere in between. But the point is that woofer excursion is more a function of damping factor and distortion than mere power. If the amp has a high damping factor then it will be able to control woofer excursion better, per watt, than an amp with low damping. It's the ability of the amp to swing enough current to start and stop the woofer and return it to it's starting point quickly. The bottoming out is a result of the woofer continuing on its trajectory after the music signal has ended. Subwoofers are prone to this because so many have too-small voice coils and/or cheesey amps in them, and because it is easy to overdrive them when all of a sudden Trex stomps by or somebody in Houston "lights this candle." I have seen and heard big amps drive reflex loaded woofers (like the Paradigm)(they travel more) to high levels without hardly any visible woofer excursion. The Bryston has a pretty good damping factor, I think, but you should check. Anything over 500 is good. My guess is that with a clean input signal the Bryston will drive the Paradigm to concert levels and neither piece of equipment will show any strain. Your ears are likely to be the first to give out!