Sound from two laptops, but with one pair of headphones.
May 26, 2020 8:08 AM   Subscribe

I wanna hear noises from both computers without having to switch input jacks. How to do it?

I'm working from home. I have a work Mac and a home PC. I don't keep personal files nor my Spotify subscription on my work computer, and would like to listen through headphones so as to not disrupt my wife, also working from home. BUT, I need to be able to hear alerts and/or conduct video calls from my work Mac. I have one set of wired headphones.

How can I mix the sound from both computers simultaneously so I can hear things from both through a single pair of headphones? I assume it's some sort of mixer, but I'm not an audio tech, so not sure what device would be sufficient.

Bonus points for a device that is roughly the footprint of a deck of cards, costs under $50 and outputs audio from the computers in stereo (for those midday ASMR vids to calm the corona-panic).
posted by po822000 to Technology (14 answers total) 1 user marked this as a favorite
Best answer: I bought this one, which is no longer available, but there are more in the recommended list at the bottom. I can't speak for any of them but they roughly fit your bill.
posted by RustyBrooks at 8:15 AM on May 26, 2020

this one might be more convenient since it uses USB for power and standard 3.5mm jacks (i.e. what comes out of your computer already) so you won't need adapters. Can not speak to it's quality or anything but this is basically the kind of thing you're looking for.
posted by RustyBrooks at 8:20 AM on May 26, 2020 [2 favorites]

"Stereo line mixer" is probably your best search phrase.
posted by soundguy99 at 8:28 AM on May 26, 2020

You want a Rolls passive mixer. Something like the MX41b is $59 and requires no power supply.
posted by mkb at 8:33 AM on May 26, 2020

If you're just streaming from spotify, they have a web player too at that doesn't require an install.
posted by noloveforned at 8:38 AM on May 26, 2020

Best answer: Just literally connecting the output from both lines to your headphones might be worth a try. There's a chance you'll get weird hum from a ground loop, but it's very unlikely to cause any damage. My recent computers seem to physically disconnect the audio when not in use, which is perfect if you only need to hear one at a time.

If you don't want to solder, an 8th inch y-adapter, two plug-to-plug adaptors and one socket-to-socket adaptor will do the job. (Y adapters are mostly made for the opposite direction. Perhaps not all of them.) If you do want to solder, two 1/8 inch plugs and, one 1/8 inch socket, and a bit of wire will do it for about $4 minus the cost of a soldering iron.
posted by eotvos at 8:42 AM on May 26, 2020

(If you do need to hear both at the same time without weird glitches, there are lots of used 4 channel mixers on ebay for $25. You'll need adaptors or cables, and they're mostly all bigger than a pack of cards.)
posted by eotvos at 8:49 AM on May 26, 2020

You may be able to set one of the computers to feed the microphone input back out through the headphone output. If so, plug the other computer's headphone output into the microphone input jack, and then plug your headphones into the final output. You'd just need a 3.5/3.5 M/M jack.

This used to be built into Windows, but a quick look at my sound control panel on W10 shows that this functionality appears to have been removed or hidden. If you have a third-party sound mixing app, you may be able to do it.
posted by Hatashran at 8:56 AM on May 26, 2020

Another option:

Install a VNC server one one machine and a VNC client on the other. Plug headphones into the VNC client and remote into the server. Include audio in the VNC options, and any audio that the server machine produces should come out the client's headphones.

Unlike Windows RDP, VNC does not lock a machine while it's in use, allowing you to use both computers simultaneously.

Requires no specialized hardware (not even a M/M cable like my previous option).
posted by Hatashran at 8:59 AM on May 26, 2020

How old are the computers? Can they do Bluetooth?

I have a set of Jabra headphones which can connect via Bluetooth to two devices at once -- normally it's my laptop and phone, but you could pair with the two computers.
posted by wenestvedt at 9:34 AM on May 26, 2020

literally connecting the output from both lines to your headphones might be worth a try

This is how I'd do it, with a standard Y-split adapter. You probably don't need any fancy mixers to hear what you need.
posted by Rash at 12:32 PM on May 26, 2020

Response by poster: I was about to purchase the recommendation from RustyBrooks, but tried eotvos's suggestion first, and while not perfect - definitely the hum - it's cheaper (had the parts on-hand). So you both get Best Answers :)
posted by po822000 at 1:04 PM on May 26, 2020

I'd just feed the headphone output from the Mac into the line in on the PC with a standard 3.5" audio cable, and do the mixing in software inside the PC.
posted by flabdablet at 6:54 AM on May 27, 2020 [1 favorite]

definitely the hum
It might be more trouble than it's worth, but adding a large value capacitor (or a "DC block," but don't use the ones meant for RF/microwave frequencies, which is most of them) in series with one or both sides of one of the inputs might fix it. Not filtering out the low frequency music at the same time is the hard part. (Buying a mixer, or building a cheap low gain amplifier with isolated inputs - which will cost the same but might be fun, depending on whether or not you've any interest in electronics, is also worth considering.) Cheers!
posted by eotvos at 8:16 AM on May 27, 2020

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