No, you have it all wrong, but thats ok, ill go easy on you
crossovers split the sound up between speakers of different sizes, sending high frequencies to the tweeters, middle frequencies to the mids, and low frequencies to the woofers.
In the oem setup these crossovers are in the factory amp, the signal from the headunit is split up and appropriate signals sent out the the correct speakers.
Installing the dynavin changes none of this, it just takes the place of the factory headunit.
There are lots of technical reasons why you cant just go changing speakers, in layman's terms they are "matched" to the amp, they have the appropriate frequency response, power handling, and resistance (known as ohm rating) etc...
This is why I suggested BSW, they have engineered their speakers to work with the factory amp and they ARE matched to the oem stuff.
So if you were to change over to aftermarket speakers and run them off of the dynavin you would need to bypapss the oem amp and install your own aftermarket crossovers, these typically would come with the speakers if you got a component set.
Also none of this addresses the issue of physically mounting the speakers, which are all non standard sizes with non standard mounting holes so you would have to custom build mounts etc.... Ive done it plenty of times and have this setup in my own car, it is not for the faint hearted.....
clear? clear as mud?