Polarity test with DMM

Is there any way to check the polarity of speakers using a DMM?

System wiring.  I hooked up 4 12" perfects off a JBL 1200.1 (2 2ft^3 boxes, 2 per box) and every once in a while it seems as if the bass skips a beat or the subs start popping.  Its more on punchy notes, long drawn out notes don't tend to do that.  I am hoping it has something to do with the polarity on 1 sub causing that. 

My radio is the Eclipse 8454, and the gain on the amp is turned up 1/3 of the way, which I know is wrong since it is then assuming somewhere around a 2 volt signal when it is getting 8. 

Could the amp be going into protect mode on those notes, and if so, why can it get louder on longer notes on the same frequency?   I plan to play with the gains a bit more this weekend if the polarity doesn't fix my problem (which I don't think that it will)  I am going to be purchasing a DMM today or this weekend to do some tests on this to learn more though.

Any other suggestions on how to alleviate this problem are welcome. 

I also want to clarify one thing... the reason I have the amp turned up (No bass boost) is because right now the front speakers are being amplified by the radio and the factory amp.  At the end of the day today, I will have the front speakers running off a seperate amplifier, which should give me some more flexibility in amp setting...

Polarity is not your problem.  More likely the amp is going into protection due to 1) impedence load is too low, or 2) input gain is too high, or 3) system voltage is dropping too low.  4 speakers, eh?  What's the net impedence on the amp?  Also the maximum input voltage this amp is rated to handle is 4 volts, so your gain should be all the way 'down" and if your HU can generate 8 volts you will still clip the amp if the HU volume is turned up too far.

A series of quick peaks places more strain on an amplifier than a sustained tone.  The peak at the attack edge (the beginning) of the note is what places the strain on the amp.

Well, the drivers themselves are 4ohm SVC.  Wired together in parallel should give me a load of 1 ohm, which the amp "should" be able to handle.  Right?

The system voltage should be fine.  I have a 200 amp alt in, and although without an DMM I can't test it, I have yet to see the lights dim.

With what you said about the amp clipping even though it may be all the way turned down, is there something I should add on to lower the voltage?  I am careful with my stuff and can hear the subs clipping, and will immediately turn it down if this situation does arise.  However, if it would be benefical for me to do that, I most certainly will.  With the said, is there another amp that may be better suited to my application?

And I was unaware of the fact of the "attack edge" places the most strain on the amp, which is good to know. 

Thanks for all your help...