Powered Sub vs. Underseat

Im looking to upgrade my system in my 05, i want to leave the stock HU. Im designing this build so that in the event i sell or wreck the truck i can easyly remove most of the stuff.
My setup so far:
stock 6 disc
SirusXM Dock
GROM-AUX-TOY(to wire the XM into the radio fro clearer signal+Bluetooth)
Scoshe Line output converter
PAC line driver(debating)
680 watt amp wiring kit

The problems im torn between is the line driver going to be nessary since im going with a powered sub? and which is better for the powered sub a bass tube or an under the set slim sub? which gives better bass for the positioning and which sounds better overall?


Any thought?????

 

I have an '06 Pre w/access Cab and am running an ARC Amp and a Focal Under Seat sub under the drivers side. I'm using the factory speakers otherwise and all connected to a Pioneer Z120BT (a real disappointment due to its terrible Bluetooth Software) I will be installing the new Pioneer Z150BH on Monday and hope the Bluetooth works better.
Anyway, I am very please with the Focal Sub for the last 3 years. I have a variable rheostat type switch located in the small cubby hole to the right of the steering wheel. I can adjust the base to suit me for a particular song.
What the Focal Sub will NOT do is blast out the base so the entire city can hear you coming. I will be stealthy and your passengers will wonder where the sub is located. But if you like the look of a big-in-your-face base box in the access cab than you definitely want to look at something else