Might be too late, but hay.

I have the Infinity Basslink-X Active Sub in my car.
(http://www.incarexpress.co.uk/focus....rtno=BASSLINKX)

My JVC HU had the two RCA pre Sub Outs, so you just buy an Amp wiring kit,
and connect the two cables from the Head Unit to the Active Sub.
(http://www.incarexpress.co.uk/focus.php3?partno=PC420)

My HU also has a remote lead, so I could use the remote wire connecting my
HU to the Amp, turning the Amp on when the HU came on.

Also, you need to connect a nice big red cable directly from the battery to
the Amp, and a black cable from the Amp to somewhere grounded on the car.

This particular Active Sub, comes with a remote, to alter the amount of bass
produced, which I attached to just under the dashboard, which is really
usefull.

That's it, easy really. Hardest part was getting the power cable from the
battery into the boot, once you've done that, it was really straight
forward.

Hope that helps.

James wrote:
hi!
I've got a sony CDX-M730 in my (old style) 3 door Corsa and wanna
install a sub. I've never done it before and don't really understand.
do I *need* an amp? I don't really wanna have to install one if I can
help it. is there an easy way to just buy a sub, connect it to the
two mono connectors on the back of the stereo, run a wire to the boot
and just leave it there? hope I've not rambled too much, but I don't
really know what I'm asking about / doing when it comes to subs.

ta very much
James