worldcat,
Passive bi-amping is fine... as long as there is no connection between the high-pass and low-pass negative and/or positive terminals inside the loudspeaker. There *shouldn't* be any, but in one case I've observed a loudspeaker that provided bi-wire terminals and had the negative terminals tied together inside the enclosure.
If you have access to a simple VOM/DVM resistance meter, you can check for continuity between the two negative terminals. You should check for the same between the positive terminals too... just to be safe. An infinitely high resistance means you're OK, but 0-Ohms or very low resistance means you can't bi-amp with any NuForce amp. Of course, if you can get inside the enclosure and break the connection, then you'll be fine... but that might void your speaker warranty.
It's always best to check with the speaker manufacturer first.
Benefits can be significant. Dynamic capabilities can increase and distortion in general can be reduced. There is one caveat though... the higher the crossover frequency to the tweeter, the less benefit you are likely to experience. For the best results, try this on a speaker that offers a very low crossover. I know of one company that bi-amping works great with. All of their speakers offer a crossover clear down to 500Hz... just like the new NuForce S-8. But... I'm not naming any names.
Take care,
-Bob
