Hello all, I am new to your forums. I recently purchased a 2007 hhr 2.2l. I have 2 questions: With the base model stereo without pioneer sub, is there an external amp somewhere or is it just the head unit?
Secondly, What would be the best location to place a small 4 channel amp where I can access all the wiring for the door speakers? Previous owner upgraded to rockford fosgate primes, and I already tapped the rear channels for my line converter to my subs. I plan to upgrade the head unit later but I already have a 4ch amp. Thanks

 

No external amp.

Depending on size there is some room behind the waterfall. Many run wires to under the passenger seat.

 

So it's possible I could tap into wires under the passenger seat for the speakers?

 

Run wires from the radio to under seat.

 

This a better pic.

 

Most logical is right at the back of the radio, the center trim just pulls out using the air vents, then undo some plugs.
There is also a thread somewhere on here about tapping the wires under the carpet inside the front doors going to the rear speakers, but sounds like you already installed a LOC for subs. The fronts can be accessed under the dash running into the front doors.
If your 4 channel has a signal pass through, you can wire the LOC -> 4 channel -> sub amp.
I preferred running speaker wires back to the rear storage area, that way you can access the battery with very short power wires (thicker and more expensive) and have plenty of room for amps. If amps are small enough they might fit beside the spare tire, or if they are big you can put them in the storage tray above the spare like I did.