The speaker you took out had no specs on it at all? Go for 8ohms if your going to do that. 2ohms is almost like sticking a plain wire across it, unless the amp is built to handle that (car amps only) your computer speaker amp mostlikely want 4-6ohm loads 8 will be a little more, just don't turn it up all the way or you could blow the output transistors/IC in the amp driving the sub.