I am connecting a new system in my truck?

i hooked up a headphone jack/RCA cable into the aux in of my HU to feed the signal from my ipod and cellular phone to the HU and use my HU's volume control as my main volume. problem is that i tend to get up to a higher volume with the aux in compared to when i play cd's to get the same sound level. i'm almost sure its a low source pre-out voltage problem. i still have an old line driver lying around and my question is, would it be a good idea to pass the ipod/cell phone signal through the line driver first then to the aux in of my HU or would wiring the ipod/cell phone/line driver straight to the inputs of my processor a better way to go? i'm sure the latter would be better but if possible i'd like to use my HU's volume control as the main volume.

my HU's an RF 8350, my processor is an Audiocontrol EQX and the line driver is a PG TBA-1.

i still think the 2nd option is better since i could level match the source to the processor and amp.

what are your thoughts on this?

2nd option