B5S4_Oz

The line out section of the h/u does not have female rca plugs. So you either splice in female rca's or buy one of these:
http://www.midwestelectronics.com/blaupunkt-4ch-preamp-adapter-p-161.html, it plugs straight into the line out section of the h/u.

Then just plug your 4 rca's in and run them to your 4 channel amp. The 4 rca's mean you will have full fader support.

Subs run in mono, they use a set of left and right signals, the amplifier sums these and provides the sub a combined (or mono) signal. There are lots of ways to connect the sub amplifer. The easiest is to buy a 4 channel amp that has rca outputs on it. You then run these two rca's to your sub amp. ZThen make sure you get yourself a sub amplifier that has a remote bass controller, so you have control over the subs volume from the drivers seat.

The alternative to running two amps or using a 5 channel amp is to:
- Leave the stock rear speakers as they are with there stock onboard amp (the rears are only there for fill and backseat passengers anyway)
- An alternative is to replace the stock rears with an effecient set of aftermarket speakers and use the h/u's on board amplifier to run these (these are the 2 front speaker level outs on the h/u)
- Get yourself a quality 3 or 4 channel amp (like an Audison or Zapco). Run your 4 rca's as above and use 2 channels for your new front splits and a mono channel for a sub or two.

Again, do a search of the forums. Information on how and where to run cables, splice in rca's, buy or make speaker adapters, pics, etc are all there.

Good luck.