I finally got tired of burning CDs and investigated adding an aux port to the stock radio. I didn't want to buy a whole new radio and I wanted to keep the stock look. I found there are boxes that plug into the back of the radio, like the PIE, but they require cutting out some material behind the dash to fit. I wasn't keen on cutting even non-visible parts of the car.

It's also possible to add an aux port on the front of the radio if you don't mind drilling a hole and soldering. There are people that will do this mod for you too on eBay. Again though I didn't like the thought of drilling into my radio.

I decided not to bother at all with the aux port and skip straight to Bluetooth. Apple infamously removed the aux port on the last iPhone. Google has done the same now with the Pixel. I expect the trend to continue and the future is going to be wireless connections.

I opted for a Bluetooth FM transmitter that plugs into the cigarette lighter instead. It's more annoying to work with than aux since it's not as simple as plugging in a wire, but that's the future

I tried one of those tape deck to 3.5mm adapters too and the audio quality was terrible. The FM transmitter sounds far better.