Simple cheap solution to plug in one pair of headphones into two audio sources (two laptops)

My other answer approaches the problem from a digital point of view, but you might not have a monitor that accepts audio or a desire to run two laptops at the same time, one being a client of the other.

If you're not shopping for a new monitor/don't have the opportunity to add audio to your monitor and are interested in a low energy solution then the simplest and cheapest solution is to do what you've already been doing; unplug the headphones from one device and plug them into the other. There are some advantages to this in the area of sound quality; every connection and switch added to a circuit is an opportunity for poor contact, increased resistance and poorer sound. A direct connection will always be best

It might not be the most convenient though; the laptops (unless the same model) will likely have their sockets in a different place, and of course the socket will likely a small black connector possibly next to another small black connector, each identified by a tiny black raised molding picture headphone/microphone in a sea of black. Which of course is replicated but the other way round on the other machine. The headphone cable may be unusably short or trail across the keyboard in an annoying way

The low cost hack I'd thus suggest for this would be to obtain two 3.5mm extension cords - male on one end and female on the other - in different colors. Plug them into each laptop and fix the socket ends together with tape, heat shrink or glue. You now have both audio connectors you need in the same place, they're clearly identifiable as to which is which and the switching mechanism is innate; you pull the headphones plug from one and put it in the adjacent one

If you fix the two connectors to the desk edge or poke them through a hole drilled near the desk edge and lead the wires under the desk it also helps keep the headphone wire out of the way while you work

In the case of a phone plus laptop, I'm not sure what you gain; you take your phone with you so when you sit at the location you keep your headphones, you have to plug the splitter device into the phone and then also switch it to the socket that the phone is connected to, which is about as much effort as just plugging the headphones straight into the phone

In the case of two laptops it makes a bit more sense but you might already have the tech needed. I have 3 laptops that I use for various tasks related to audio and I need to listen to them at various times

Two of the laptops are connected via HDMI to a monitor that has a headphone socket - the monitor plays the audio from whichever screen it is showing so the switching of audio is implicit from having switched the monitor to show video from laptop A or laptop B

Laptop C is a small thing with an unusably small low res screen so I tend not to use the laptop itself by sitting at it and looking at its screen. Instead I remote into it (because then it adopts the screen size of the larger machine) using Remote Desktop, and one of the options for RD is to bring any audio that the remote device plays, to the local machine

This means in my case that I can just leave the headphones connected to the monitor and when I'm working on laptop B, I hear the audio via the monitor.. similarly when I'm working on laptop A I'm using it directly and near the audio it plays via the monitor. When working on laptop C it's via laptop A, so I hear laptop C's audio because RDP pulls it to laptop A and plays it there

Though I don't have it set this way in this setup, elsewhere I have a laptop that serves as a Bluetooth stereo headset for the phone; when the phone plays audio it is transferred to the laptop. If your laptop has no Bluetooth but has a line in you could arrange a similar setup

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All in it may well be possible to arrange things so that you leave your headphones plugged into one device and then use that device as the aggregator of your audio streams

If you want to be able to listen to audio from the both laptops at the same time, there is no simple or easy hack - and especially not safe, it can even damage the electronics in the laptops.

The safe way would be:

1. Buy an external USB sound card - mandatory with a line-in connector.
2. Connect and install the USB sound card to laptop 2.
3. Connect (with a proper audio cable) the audio-out of laptop 1 to audio-in of the USB sound card in laptop 2.
4. Connect the headphones in the audio-out of laptop 2.

It can work also with a smartphone. The smartphone replaces "laptop 1" in the setup above.

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If the microphone needs to be used on the both laptops simultaneously, I am not sure what to do. A simple Y splitter might do the work, but there is some risk in electronics damage a well (as explained above).

Note: I cannot be sure about this, since I do not know how the microphones are powered - there might even be several technologies involved.

Example:

• with independent connectors (1 for headphones, 1 for microphone), there are 2x3=6 contacts / lines; present usually in headphones for computers.
• with a 1-for-all connector, there are 1x4=4 contacts / lines (usually for smartphones), 2 less then the previous.

Someone with better practical background in electronics might be able to give a better answer.