connecting passive speakers to my Mac Pro

I recently received a couple of Behringer passive studio monitors as a gift and I'd like to connect them to my Mac Pro.

I know I can't connect them directly, and would need some kind of amplification in between. My question is; can I use something like a home theater receiver (I have some cheapo Sony "home-theater-in-a-box" receiver in storage) to amplify them, or do I need to purchase an actual amplifier?

Thanks in advance.

cool - thanks.

I've been looking around and I may still buy an amp if I can find one for less than $100. I just realized I don't want a giant silver Sony eyesore on my desk top. I didn't even want it next to my home theater...