I was recently in Hong Kong and decided to purchase a knockoff Airpod to tear it down and see how it was engineered to help me in my own design process. I got to the mainboard and found the single chip which runs the operation marked "AC1815E8K193-9A0" (It may also be "AG…") and uses a logo which looks like the Pi symbol. A search turns up nothing and I'm struggling to find anything online about this model. Any ideas of where to search or any leads would be much appreciated! I'd also be glad to provide more pictures if desired 
Electronic – HBQ-i7 Bluetooth Chip Identification
bluetoothidentificationintegrated-circuit
Related Solutions
It might be a custom chip built by Gennum/Semtech. The numers on the chip seem to correspond to those of HD-SDI cable drivers they make (e.g. the GS1678), in particular 0002E3 should be batch number 0002 (this very low batch number and the absence of an identifiable part name make me think of a custom chip), E3 on their packages is meaning RoHS compatible, and 1352 should mean that it has been manufactured on week 52 (end of December) of 2013.
The chip looks very similar to their GS1678 HD-SDI cable driver it has the same QFN16 package, and the pins seem to be used for similar/identical purposes:
Image from datasheet
In particular, you can notice that pins 9 (VCC) and 6 (DISABLE*) are connected together, which perfectly makes sense, and RSET (pin 4) is connected as required to a resistor (possibly going to VCC through the via). The top four pins are not connected (except maybe pin 16? not sure from the image where the track nearby is going), the DDI pins (1/2) have two ceramic capacitors nearby as expected per datasheet, and the output signal (going to the BNC through the matching network) seems to come out from SDO (pin 12) as it should.
That's an Analog Devices AD8312 50 MHz TO 3.5 GHz, 45 dB RF Detector.
Best Answer
Here's one I found when searching JL chip logo: -
Note that this is an AC.... part so try and find who JL is....
But the chip number doesn't match the AC6905A number so maybe they use some form of coding.
Following the part number protocol used in the picture your device might be an AC1815E from JL (who appear to be based in China). Maybe it's related to JL audio who make weatherproof bluetooth modules: -
See also this SE question and this one where others have tried to find parts made by these guys but not very successfully. Good luck.