Is this a stupid question or something?

i only ask this because i don't believe the 125 has a biamp option

Why does he want to biamp them? What does he hope to achieve?

to get more control over the setup and get better sound/performance from an active x-over. The seperate amp controls work on the amps. Obviously better sound is the final goal.

It seems like you would be wasting half of your amp in doing so. Biamping is nice for when you want to run different amps to exploit their characteristics (such as using one type of amp on a woofer because it has an excellent damping factor but may be cloudy on the top end and using another for the tweeter because it of its smooth top end but week bass).

sorry, i should have been more clear. There'd be two 125s. Bottoms of both on one amp Tops on another.

Really, this is a question more suited for the people at diyaudio.com.

On that know, I understand what you are trying to do. I just don't think that you are going to make the rig sound better by doing this, but then I am not familiar with these speakers. Still, those qsc's have a lot of power and unless you really love how they sound through a high frequency driver, you are wasting a huge amount of potential that the amp has to offer. If you do love how those thing push the high's then you have to consider the quality of your active x-over. It just seems like more trouble than its worth, but maybe not. If you're really set on it, give it a shot. You can always go back.

Obviously these speakers already have passive x-overs in them so another option is to look at the TS parameters of the drivers and redesign a passive x-over based on these. With good components and a good design you will notice a big difference. Start lurking around diyaudio.com for more info on both biamping and x-over design.