I am installing an upgraded stereo into my wife's MDX. I ordered MBQuart Reference 6.5" components for the front and an Infiniti Kappa 104.7 subwoofer. I plan on using my amps and head unit that I have stolen from the Talon, Soundstream EGA2160 for the fronts and a Punch 40ix for the sub.

After a little more reading I found out that the subwoofer is dual voice coil and selectable 2 or 8 ohm operation. It is available in a 1/4 ohm configuration as well. Not knowing much about car stereos, I am wondering if I can use this sub with my current amp, or do I need to get the 1/4 ohm version?

I have searched everywhere and never really found a straight answer.

Set the sub for 8 ohm operation and you should be fine, as your amp runs at 4 ohm. AFAIK you cant run a sub at a lower impedance then your amp can put out.

Oh you can DO anything... *Laugh*

This is the basic stuff I learned WAY back in high school:

Let's say your amp puts out 100w stereo into 4ohm speakers. You bridge it so you're getting 200w mono.

You hook up a 4ohm sub that is rated from 100w-300w. You're working as advertised.

You have 2 2ohm subs? Hook them up on series, (Positive to Negative speaker-to-speaker) and you get a 4ohm load.

You have 2 8ohm subs? Hook them up in parallel, (Split the wires so positive from the amp goes to positive of each speaker) and you get a single 4ohm load.

Here's where it gets more interesting. When you increase the resistance (Ohms) of the speakers, wattage output drops. So if you use a 100w 4Ohm amp to drive an 8Ohm load, you're only getting 50w output (so lower volume). When you go the other way, and drive a 2Ohm load with the same amp, it outputs 200w. But it isn't *free* power. Think of it like driving a 10-speed bike down a hill in a lower gear at high speed. The amp will 'exhaust' itself quickly from the higher output, you'll get higher distortion levels and increase the chances of blowing it or the sub out.

You can get away with it if you know what you're doing, just don't overdrive speakers or amplifiers too much. The quality of the gear is VERY important at this point as well.

Older Rockford amps would run 2 ohm mono all day, I don't think the newer ones will though. I had an original punch 40, yours being an ix sounds a little newer. Might not handle 2 ohms but you could look up the specs and see if it is 2 ohm stable.

I think it is around circa 1996. I've had it for so long.