Audio Question - Amplifier Hookup

[BigRed]

For any of you car audio guys, I need a little help. It's been like 15 years since I've wired an amp in so I have some questions.

I have an amp that I'm wanting to run both channels into one subwoofer. My memory tells me that I can run one channel's (+) to the woofer's (+) and the other channel's (-) to the woofer's (-). Is that correct? Also, I have a setting on the amp for 2 ohm and 4 ohm. Would I want to run 2 ohm with this bridged-mono setup?

Just to let you know what I'm doing. I recently bought some 2way Audiobahn 3.5's for the dash and 2 4x10 components (with crossovers) for the rear of my suburban. I plan on running those off of a new 50w per channel head unit and then I'm going to run a sub (not sure which yet) off of a 400W kenwood amp. I've already hooked up the mids and highs to the old crappy head unit I have and it already makes a huge difference. I can't wait until I have everything hooked up.

I'm currently going through a divorce and that's why I haven't been on in awhile. And that's also why I'm now starting to do some more stuff to my truck because I have more free time now.