I just completed round one of my radio upgrade. The biggest issue was the Harman Kardon amplifier, which to be honest, never seemed to do much for me. I have an R52, and I'm told the HK is different than the one in the R50/53, so you may not have the same issues that I did. The speaker setup is definitely different for the R52.

First thing I did was I bought a wiring harness that allowed me to enable the HK. This unfortunately, did not work - it would not enable the amp, and I would get no sound.
Then, I bought an HK Enabler - which seemed eerily similar to the generic harness. This also did not work for me. The amp would not turn on, and I would get no sound.

I tried wiring the "amp" output on the radio straight to the amp, and enabling the amp in the radio. This also did not work. So it seemed that using the HK amp would not work - which is fine by me, since it didn't seem to do much, and the android unit has a full equalizer and balance/fade which would be lost with the HK anyway.

Looking around, It seemed like I had no option but to replace all the speakers, and rewire them straight to the radio. So I started down this path.

I replaced the right front speaker. Since I needed to remove the HK amp and pull wires down, I removed the passenger seat and side trim, pulled the HK tray, and unplugged the amp. And then I realized - well, it runs the speaker wires all to here, so I might as well run *my* wires here, and then splice them into the output wires, and then I have much less wire to run.

So using the color coded wire from the speaker, I got the front right input, and connected it to the same color wires that I saw on the front right bottom speaker.
Plugged up my new radio with the harness, and turned it on.

And it played. But NOT to the front right speaker. The colors coming from the HK to the front LEFT speaker have the same color wires that are on the front Right speaker!. The music played fine from the head unit to the HK speaker on the left!. So I wired up the left tweeter - and it worked also! After a bit of discovery on what wires went where (just connected the input to each output), I wired the front speakers and tweeters up, and it all worked, and was plenty loud for me just with the head units built in amp. It's a bit more tinny than I would like, but I think that is because I have the coax speaker and the tweeter both connected on the right side.

So I came to the conclusion that you may not have to change speakers. And since the head unit already sends front right and front left to the amp, you can just wire those directly to the front speakers. (you wire both the woofer and tweeter together, to each input, the tweeter has a filter on it).

I did pull off the trim so I could make sure which wire was positive and negative (connect a nine volt battery to the speaker wire, and if you guess pos/neg correct, the speaker pushes out. If you guess wrong, it pulls in).

I also found that there are two sets of wires that go to each rear speaker. But they are both wired directly to the speaker - there is no tweeter in the back. So you can just ignore the second set of wires. No idea why the second set is there - maybe the non-cabrios have a different setup in the back.

I had previously added a backup camera, and this unit has a video IN, and you hook the power from the bkup cam to the "back" wire, and the backup video cuts in when you go into reverse just like you expect (and it's much nicer than the tiny screen I had before for the cam).

The unit I ended up getting was a Joying 6.2 single DIN unit:

https://www.joyingauto.com/android-1...l-buttons.html

If you put the mounts on the screen as far down as it can go, then this unit will not block the speedometer or the air controls.