Soundmanred

I finished my install last week in my '07 TL-S and had some observations, mostly concerning the sub channel.
I kept the factory nav/audio unit, and the factory amp only powers the center channel. I ran three sets of RCAs from the factory amp output to the JL900/5- front, rear and sub. The JL900/5 takes speaker level inputs via RCA (you have to splice RCAs onto the speaker wires from the factory amp).
I was controlling the sub level from the HU before getting the remote level control (RLC) for the sub section on the JL900/5.
It just didn't sound right at all, the bass had a weird response and just sounded off. (FYI, I've been installing car audio for 20+ years.) I tried adjusting the subwoofer level on the HU to just about every setting from the lowest to the highest with no difference/improvement.
I have a feeling that either there is some equalization going on for the factory sub, or the signal from the factory amp is just disproportionally stronger than the front/rear outputs.
I switched the amp to recieve the signal for the sub section on the JL900/5 from the summed front/rear inputs and it sounds way better.
It's flatter in response and more balanced, and much easier to control.
Now it sounds great all around. It's the first time I've kept the factory HU and it sounds as good as a other install I've done. (and the JL900/5, being a full range class D, sounds just as good as any class A/B amp I've used!)

Here's what I have installed:
Factory Nav/Audio
JL900/5 5 Channel amplifier (100x4 + 500x1)
CDT components in stock locations in the front
Alpine SPR-17C rears (I usually don't use rear speakers, but my kiddo likes music back there!)
Treo TSX 12" subs (2)

Trunk Monkey

iTrader: (1)

I'll help a fellow Okie! Did you take the signal before the factory amp or after?? My guess is that you took it after and when using the sub signal you were seeing that it's already crossed over and were running a crossover on the 900/5 also.

jda123

Did you disconnect the noise canceling microphone? I don't know where it is since I don't have a Type-S, but you can probably search on it.

The JL amps will accept the pre-amp signal if you want to take the turdish stock amp out of the mix - just switch the input sensitivity to low (or whatever it is) after you do.

Trunk Monkey

iTrader: (1)

The Noise Cancelling Mic in the TL-S is in or near the dome lights. I believe you just remove the cover and it will pop right out.

Soundmanred

I didn't unplug the mics, I unplugged the box under the center channel instead, much easier that way.
The signal was post amp, and sounded crappy even when turning off the x-over on the amp.
The sub signal seemed to be EQed funny, and I knew the signal for the fronts was full range and had a flat response, so I just used that instead. It was unnecessary to use the sub signal anyway, I'm not sure why I wasted my time and cabling doing so.
It sounds great now, so no help needed, this is just an observation for those who might find themselves unsatisfied when using a similar setup.
It sounds amazing, and I highly recommend the 900/5 for those looking for a compact yet powerful solution. I installed it under the driver seat and there are no issues with clearance or temperature. That also kept my power and signal wires as short as possible, and my trunk is amp free.
Other than the subs, it looks stock.

I hate cars

The HD amps are great, I have one under each seat. I've seen the sub section of the 900/5 put out 580w in independent testing and supposedly they put out even more into a reactive load. I was a little worried about downgrading from my old setup with 1,300w to the subs to 500w but it pushes them near their mechanical limits so it's plenty.

A big difference from my old class A/B setup is run time with the engine off. It's more than doubled. As I understand it, not only is D more efficient but A/B pulls a ton of power regardless of volume where D ramps up the power proportional to the volume.