I'm trying to record on my Mac book pro early 2015, but the Line-In port does not appear. I only have the "built in Mic" option. I have plugged different kinds of mini jack in the only in/out port, with the device already turned on...and NADA.
You don't have a line in.
Per the Technical Specifications for your MacBook, it has support for a line out, but not line in.
- Stereo speakers
- Dual microphones
- 3.5 mm headphone jack
- Support for Apple iPhone headset with remote and microphone
- Support for audio line out (digital/analog)
To get a Line-In, I suggest using a USB-DAC or a USB Mixer so you can get a proper line level input and output. In fact, I try not to use any of the built in audio ports due to their poor shielding and "economy grade" components. You'll get better results with a proper audio interface.