Hi guys,
I am somewhat of a newbie here. I apologize for posting a question that may have been covered in other posts but I could not really find my answer from previous posts.

I have B8.5 S5 with the standard audio system (Non-B&O). I just ordered replacement door speakers for the car. picked up a pair of Focal 165AC coaxial speaker with a set of baffles to replace the OEM speakers. I understand that the front door speakers are hooked up to same speaker output line as the tweeter in the dashboard. would having a coaxial speaker in the door panel cause an issue while the dash tweeters are also enabled? I have read that the stock amp does not send signal below 100 Hz to the front but would it cut off high frequencies to the door panels as well?

now, moving to the main dilemma. Without even having the speakers installed, I am guessing that the stock amplifier is not going to do any justice to the new speakers which brings the amplifier question up.
I really don't care for additional bass and rattle in the car however I do like to get better mids and highs as well some definition out of my new Focal speakers (once installed that is ). I was either thinking about replacing the entire stock amplifier with an aftermarket amp like a Alpine PDX-V9 which is a 5 channel amp (going from 6 channels to 5) or add a very small 2 channel amp like Alpine KTP-445U (in bridged mode) in addition to the stock amplifier to just drive the Focals. Has anyone added a small secondary amp next to the stock amplifier?
As far as wiring, what is the best way to tap into the stock amplifier wiring harness without ruining the harness? If I were to go with an additional 2 channel solution, I would have to tap into the Line output L/R and Line output ground as well as removing the front speaker output lines from the amp and tap into the remote/switch positive of the harness. I don't know how to properly expose and splice wires without ruining the harness and avoid any noise problems. Any assistance in this area is greatly appreciated.
As for the complete replacement solution, I would have to basically remove the center channel from the system. I may have read that the Bluetooth phone system is hooked up to the center speaker, is that correct? Also, Is there any adapter that could be attached to the stock amplifier harness to get the line-in and speaker output lines without messing with the harness itself?
Thanks in advance for your time.

 

I'm about 4 years late to the party!!
just wanted to know how you got on with it? I'm in a similar position, except I want to amplify all 4 doors and install a sub with a 6 channel amplifier. Leaving the 2 dash tweets and the centre coaxial to run off the Audi amp.
I've read somewhere that by passing the Audi amp will cause issues though.