time for the pro audio overhual NEW PICS..
Reply #1 –
A "Pro Audio" (which by definition would be audio gear used in a studio or public address system) sub over a good car audio sub isn't going to make a big difference in "muddiness." Because of the interior of a car (no parallel surfaces, no 90's, etc...) there is little to no chance of standing waves (dips or peak in low end frequencies) forming. The only thing you'll do by using "pro audio" speakers in your car is create mismatched impedances...
Also, whether it's studio or live, all the low-end should come through the subs, assuming you know how to properly adjust your crossover...