My current hu is a pioneer deh-5900ib with the blown pico and alt whine... never hot swapped and its properly grounded but it still happened, guess I could fix it... Never worked around a circuit like that, but hey might as well start sometime.. And i have thought about an external x-over before and yes that is an option, but it would be nice to be able to control everything from the hu, and i guess burr-browns would be a plus too, as my current hu doesn't... And to M5, um overall smoothness could be slightly sacrificed for a little more sharpness and detail on the high cymbal's I guess. Sadly I can"t really tell you any tweets that I've heard and really liked, If i go to a car audio place to demo around here I'll be greeted with poor service, small selection with the highest end stuff consisting of low-mid range polk. ...mounting locations, and don't kill me now lol..... mids in stock location(well of course cut out and baffle made to fit) And tweets I would also like to keep in the door somewhere, maybe right next to the mids.... I keep my seat on the floor and the stock location is actually decently high up, however I am willing to play around with the tweets location and aiming and will consider placing them elsewhere if it is a big enough difference to me.... I am willing to fudge my budget a bit if i really really need to.