well as long as both speakers are wired the same way it wouldnt make too much difference,if its out of phase its pretty easy to tell, it cancels out more than youd expect. when i accidentally had my two new subs plugged in out of phase, i was ready to throw them back in the box and take them back ! (luckily i was NOT an idiot and i checked everything over and found that in about 30 seconds

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noise cancellation is an intersting thing. a friend of mine has headphones that have a built in mic, read the outside noise, and produce off frequencies to cancel them out. put them on, and its like the whole outside world is put on mute. they are SO damn cool. pricey tho
