How to Bi-amp??

I realize this is a stupid question, but always wanted to know and have two amps, one doing nothing.

I have bi amp able speakers and a 305 wpc amp, and another 255 wpc amp.
I like to try running the 305 to the drivers and the 255 to the midrange and tweeters.
Is this very difficult to do? Could you tell me what cables I would need to do this?
I have enough speaker wire to run from the amps to the speakers, just not sure what I need from my preamp to the amps.

Sure appreciate it.

Thanks to all that reply.
Your preamp would need to have dual outputs on it, if it doesnt have dual outputs, then a "Y" connector could be purchased for very little money.

You of course, would also need another pair of speaker cables for one of the amps. Dont forget about IC'S as another pair of those would also be needed.

If I have left out something, I'm sure others will respond to this and help you out.
Riley804 is right on. But if you're preamp doesn't have two sets of outputs, using a cheap Y-connector will decrease transparency. You may end up driving the speakers better, but you may also add distortion.

I also recommend utilizing the identical interconnects and speakers cable for both amps to achieve the most cohesive sound.
I guess I should of included, I have a Audio Research SP9 MKII preamp, I beleieve I just have a main output.
This was just a thought. I hate to use a cheap Y connector. Thanks for the replies!!
I am also in the planning stages to bi-amp, here's what I've come up with so far. I will be getting a Behringer digital crossover to bypass the ones in the speaker. So, it's source to pre-amp, then to crossover, then to the power amps (there's also one more output to include a subwoofer). You can use any speaker wires that you fancy, but you will need more interconnects for the extra hookups.
Just curious, to switch gears a bit, how do you like your Consonance CD player? I bought one, and I think it's great!
I have used Monster Cable Y adapters for a similar purpose with good results. Try it and let your ears be the judge.

However, there is another consideration. Not all amplifiers have the same amount of gain. In other words, as you increase the volume both amplifiers may not increase in volume at the same rate. This could result in a much different mix at different volumes. Either check the specs in the manuals or let your ears be the judge.

One last thought... If the gain is not an issue, don't assume that you'll get the best sound with the larger amp running the bass. Both of your amps are strong enough to drive the bass, so try it both ways. I'll bet your determining factor will be the amp driving the mids and highs, not the other way around. You'll want the more detailed amp for the mids and top end. The whole point of bi-amping is to relieve the amp running the mids and highs of the burden of driving bass so it can have plenty of reserves for transients where our ears are the most discerning. Let your ears be the judge.

Good luck and let us know how it goes.
I have been told that using two different brand of amps or two different power rated amps is a no no for biamping one set of full range speakers. However my speakers are biampable and once the bridging straps are removed the horn section cannot exceed 35 watts and the bass drivers cannot exceed no more than 100 watts. Using two 100 watt amps in this scenario could damage the horns by overdriving them, so why couldn't you use at least two of the same brand amps but with different power ratings for this application? Anyway conrad johnson told me there is a high quality device that will convert one set of preamp outputs into two and the end result is identical to a preamp designed with two sets of preamp outs. This is not a Y adapter. I am going to pursue this with CJ.