I have a 6.5" bazooka sub box at 4ohm...
question is, how much power will I need to run it sufficiently..?? I am not looking for anything heavy, just need a little thump here and there....
should I look for 2 channel bridged and what wattage should I look for ?

anyhow, thanks in advance..btw I have alpine CDA-7840

 

You don't need much power, just get something around 150 to 200 watts. That should be enough.

 

150-200 is too much,,,,you are looking for around 60-100 max for only a 6.5" sub........only requires a very small amp.