setting up new headunit help

so i've got a bose stereo with a cheap and cheerful sony with an autoleads adaptor. worked fine but headunit died so i bought a new one, a kenwood KDC-W7031 (Kenwood KDC-W7031) with ipod interface. problem is the new HU is seriously complex with the ability to adjust speaker types, HPF, LPF, cut offs etc etc. any good links to help me understand how to go about setting it up or a good place to start. so far it sounds super crisp and clear which is great but lacks bass through the sub. infact all the sound seems to come out of only the rear speakers! any ideas? or are these kind of stereos only suited to 'proper' installs.

any help appreciated.

Steve

would i be better selling the bose set up and running the speakers off the HU with a separate sub and amp?

so heres a new plan. i have heard good things about these for the money as front speakers...
EDGE ED305 5" 2-WAY COMPONENT SPEAKER SET (210 Watts) on eBay (end time 14-Apr-11 16:56:03 BST)

i have some old fusions i can stick in the rear and i can make a stealth sub running an 8inch sub

maybe something like this
JBL 8" 800W CAR BASS SUB SUBWOOFER 20cm LOUD BRAND NEW on eBay (end time 27-Apr-11 23:22:04 BST)

with an amp like so (bridged)....
JBL GTO752 GTO-752 2 x 75W RMS, Amplifier,AMP 2 Channel on eBay (end time 04-May-11 15:11:02 BST)

i know a far bit about car audio as my other car has mb quart, rockfort, alpine etc but i want to do this cheaish and have always liked jbl for the price.

i reckon i can do this for about £100 and sell the bose for the same...what do ya think?