Originally Posted by atebit

CK6Speed, was there something in particular that made you think the factory amp has a 12V turn-on? Every source my installer consults gives him a different answer. He seems to think the aftermarket install will be easy if there's simply a 12V turn-on lead.

It would be great if one of the "standard" Lexus/Toyota amp bypass harness that installers use might work, but none of the manufacturers of those harnesses have gotten around to cross-referencing them to the RX yet. I guess it has to do with the newness of the vehicle plus a low demand for info on these vehicles.

Originally Posted by CK6Speed

I don't know if the non ML system in the RX400H is different from that in the regular RX330. If it is the same then removing it is no problem at all. No other functions will be lost. Well, you will loose the steering wheel controls (Unless you get an aftermarket steering wheel control interface), and you will loose all the functions of the OEM radio obviously

In my 04 RX330 standard non ML car, I removed the OEM headunit and replaced it with an Alpine IVA-D300 flip out monitor and an Alpine PXA-H700 surround proccessor. I used an OEM Harrier double DIN replacement trim plate like the one posted in the post above. I also put Alpine touch screen monitors in each headrest. I bypassed the amp and used my own amps powering the stock speakers. The PXA-H700 has individual x-over and EQ settings for each speaker, so that is how I handle the tuning to each speaker.

As for the wiring, it was easy. I simply unplugged the speaker connectors coming out of the stock amp and tapped into the correct speakers. This was the easiest way for me because I didn't want to run new speaker wires especially to the dash speakers.

Keep in mind, this was for my RX330 no ML system so I don't know of any changes were made in the RX400H non ML system. I can't see why they would though. Oh, also mine was a non navigation car as well. I heard the navigation cars are a little more tricky as some of the power to the climate control unit runs though the radio.
I can post up some pics of you want.

Originally Posted by atebit

CK6Speed, can you please tell me where the factory amp is located on your vehicle? I had heard that it's under the cargo deck someplace on the RX330. I don't know if it's in the same place or not on the RX400, since there are some parts of the hybrid system back there somewhere (the battery, DC/DC converter, etc.) However, at least if I know where it is on the 330 that will at least give me a place to start.

Also, do you happen to know if the factory amp is enabled/turned on by a simple 12V signal, or does it require some special logic from the radio? My installer says that if it's a simple 12V turn-on, I can probably get away without bypassing the amp, but if it requires some special "data" signal I'll probably end up having to do a bypass. That'll be a pain if the radio's up front and the amp is in the back...