Jean Carlos

I am doing some research to add an aftermarket 4-ch amp to replace the 4 door speaker on my 2nd Gen MDX (08). From my research I think it would be better to tap the Head Unit output into the the factory amp and run RCA directly to the aftermarket amp (without LOC) to avoid noice and cross-overed signal. I have found some people agree with my plan. For example
These posts:
https://acurazine.com/forums/audio-v...d-unit-280386/
https://acurazine.com/forums/3g-tl-a...utputs-822470/
https://acurazine.com/forums/2g-tsx-...preamp-819501/

Other people disagree stating that the Head Unit output voltage is too low and you will need to compensate using the amp gain.

Base on your experience, what do you guys recommend.

SQLnovice

I'm in the process of adding 3 amps and a JBL MS-8 processor. From reading online, I will tap into the front speaker wires preamp. From my understanding, the front speakers are full range (20hz to 20khz). The stock amp will be unplugged and will not be used. I have a 2012 MDX with the base stereo. Fingers crossed hoping I'm correct.

locorecto

Thanks @SQLnovice for the advice. Based on this post: https://acurazine.com/forums/2g-tsx-...preamp-819501/ I would loose the ability to control "volume, tone, NavVoice, BT or mute control when the HU changes modes so it will pop like heck"

I ended up using tapping the stock amp output into a NVX XPLOC4 LOC into my aftermarket amp. The sound is very nice. The only thing I would complain is the overly boosted highs. I am still tuning it.

locorecto

I meant to say * I would loose the ability to do lost of thing if I tap before the stock amp.

Bchester6

You can only do this if your amp has balanced inputs but is a lot better option than speaker level inputs. A balanced signal with no distortion, regardless of how weak the signal, is going to be tremendously cleaner than a post amp signal from an OEM amplifier. This is especially true if all of the sound processing is done in the OEM amp.

locorecto

Thanks @Bchester6 for your input. I do agree that, in theory and using the better equipment, taking the signal from the head unit without processing or amplification is the best option since the signal is going to be a lot cleaner. This was the conclusion I got to after doing my research.
In practice, when talking specifically about the ELS system, this is a little difference because

• Based on the link that I posted in my previous post, by taking the signal before the amp I would loose the ability to control "volume, tone, NavVoice, BT or mute control and when the HU changes modes it will pop like heck". In my case the trade off is to lose all that and use the HU signal or take a little distortion, which is negligible in my case, and take the signal after the stock amp into an LOC. I wasn't willing to lose all those functionalities so I opted for the latter.
• If I end up taking the signal from the HU before the stock amp, the signal is too weak for my low-to-mid-end amplifier to do a decent job. According to my research the signal coming from the HU is 100mV to 200mV signal. I would either need a line driver to increase the signal strength or a better mid-to-high-end class D+ amp. Since I am on a budget and I am only looking for a modest improvement in my sound system, I am not willing to spend that much more on the best equipment.

I might be wrong but that was my conclusion.