Right now I have both a laptop and a desktop, and would like to be able to use both the headset and mic of 1 headset on both computers at the same time. I believe something like a splitter (like this) that sends both the audio and mic to both ends, if that makes sense. Or would a mixer be absolutely required. I'm not trying to drop a lot of money on this, and I already own 2 3.5mm to usb adapters so it would be really easy just to split it. (Something like this) Any help would be appreciated.
If you don't have separate mic and headphone plugs then you will need an splitter that does that. It will have a four conductor jack and both 2 and 3 conductor plugs
You can connect the mic input of both computers with a two conductor splitter.
You can't usually split the headphone input and connect that to the headphone output of two computers. That would connect the headphone outputs (or the USB adapters) to each other. You could use a passive mixer.
Altoids Tin 1/8" Stereo Mixer: My car stereo has only one 'Aux' input, but I have several gadgets that I like to hear on a trip without swapping cables: MP3 Player, talking GPS, Blackberry, XM player, Kindle, etc.I couldn't find a commercial solution, so I came up with this lit...
I did a little research based on some of the things you said and figured out what I (and anyone else who wants to do this) need is a single female TRRS (Tip Ring Ring Sleeve) to 2 male TRRS splitter. TRRS is what allows both the stereo recording and stereo output, and is what is needed for one plug to act as both mic and headphones that we see on phones and laptops today. So I believe, and will update when i know for sure, that plugging the headphones into the female TRRS plug, and plugging both TRRS males into the 3.5mm to usb cables (which is mainly acting as an extension cable) will work. I updated my diagram here to show you what I mean. Also this is the splitter I will be testing when it arrives. Anyways, thank you for your help.