The best way to determine the impedance of a speaker is to look for a label or marking on the speaker. Second best is to look the speaker up in the manufacturer's specifications. Measuring a speaker with an ohmmeter does not work, because you need the average impedance at AC, not DC. You could measure the current and voltage coming from the amp at various frequencies, but you may need to compensate for phase shift, and that procedure might not agree with the manufacturer's procedure. If you are going to look up the manufacturer's procedure, you might as well look up the speaker's impedance instead.
If your sub is 2 ohms and your amp is 2 ohm stable, your done. Your amp will be at 2 ohms because the sub is 2 ohms.
It is the impedence (coil resistence)normally sub component (drivers)are in 8 ohms impedence.2 in parralel is 4 ohms and 4 in parralel makes it 2 ohms.
You bridge the amp not the sub.
4, the lower the better
The problem you have there is that your sub woofer needs both coils wired and your options with that setup is either 2 ohms or 8 ohms depending on if you wire the sub itself in series or parallel. If you use a second sub like the first one and wire both subs in parallel and then wire the two subs in series you can achieve 4 ohms. You could also wire the subs in series ( 8 ohms each ) and then wire them in parallel to achieve the overall 4 ohms.
i dont now
1000 ohms.
That is 366,300 ohms.
3500 Ohms
1000 Ohms = 1 kilo (not killow) Ohms
1.2
4 ohms