bi-amping is using one amp to drive the low frequencies and another for the highs.
So you'll need another amp and another set of speaker cables.. You must also make sure your pre has 2 outs that put out the same signal or your amps must be daisy chainable.
I'd say bi-amping is similar to the added traction a 4 wheel drive vehicle has over a 2 wheel drive vehicle in the mud. You'll get better detail and more resolution by bi-amping.