Yes I have coaxial 6x9s up front and component 6.5 in the back with out the tweeters and crossover overs connected. My truck has the pioneer double din with a mosfet 50x4 amp built in. It sounds good just wanted a little more highs for the type of music I listen too. I am new to car audio. I tried connecting the crossovers directly to the 6x9s with the tweeters and it did not sound good . Tweeters were not making any of the highs I was looking for. My truck did not have the tweeters in the front or any cables leading to it. Was trying to see if I can connect the cross over for the tweeters to the 6.5s in the back from the head unit? How can I make it sound better with speakers I already have? thanks
I'll go straight to the last question, but it's up to you if you want to do the work:
"How can I make it sound better with speakers I already have?"
1. Pull the 6x9's from the front doors, sell them to get some cash back.
2. Get some 6x9 to 6.5" adapter plates for the front, about $10.
3. Run a pair of decent speaker wires (at least 16-gauge, personally I do 14-gauge) from the front kick panel; one pair of wires into the door (through the door jam), and one pair of wires up the dash to the speaker locations at the top of the dash.
4. Install the crossover in the kick panel.
5. Connect the front L/R channels of your Pioneer head unit to the crossover inputs.
6. Connect the door front speaker wires to the "midrange" output of the crossover.
7. Connect the front dash speaker wires to the "tweeter" output of the crossover.
8. Install the 6x9 to 6.5" adapter plate into the front door speaker housing.
9. Connect the front door speaker wires then install your component 6.5" in the adapter plate.
10. Connect the front dash speaker wires and install your component tweeters in the dash location.
There you go - just 10 steps, pretty straightforward, and I guarantee your music (whatever typs it may be) will sound a lot better (unless your component speakers are low end).
If you itch for more after doing the above, look into getting a small powered subwoofer for some low-end bass to round out the sound.