reading about some unfortunate situations with blown drivers (on other forums). The #1 preventative measure was to NOT randomly load some aftermarket speaker in whatever cabinet is laying around. Cabinets and drivers need are engineered to work within certain parameters and a specific driver requires a cabinet with specific characteristics. But close behind that was the #2 suggestion - utilize a high pass filter to avoid sending frequencies down below the cabinet frequency. Now, many amps have a filter built in; but even more do not. Short of buying a new amp, or some high end pro-audio EQ box that includes a hi-pass filter is there any other way to incorporate this kind of protection into your rig? Especially for anyone who gigs with a single speaker (1-15 cab, typically) and needs to rely on the "health" of that single speaker.