Summing two stereo inputs to one output

[somnif]

So, odd question for the crowd.

I wear wireless headphones at home, pretty much 24/7. 99% of the time they're hooked to my computer for general use, but I've been gaming with the old ps4 this summer so occasionally I'll swap it over to the TV.

My question is, would there be some economical way to keep both the TV and Computer hooked up to the single output of my headphones simultaneously? I know its not as simple as a female Y-splitter, but looking up things like mixing boards and headphone amplifiers is getting confusing in a hurry.

I don't need 18 channels with a dozen knobs of frequency and gain adjustment. Just looking a way to have two stereo inputs going to one stereo output.

Any ideas? I'm on a teachers budget which means I'm broke as hell and won't see my first paycheck in 3 months until the middle of September so... cheaper is better.

[Willybomb]

I suppose you could do 2 of these, using one each for L/R....

[madbean]

This is a similar idea to what Willybomb posted but how I would personally start on it. It's got a little bit more going on but everything has a purpose.

1- Small amount of amplification for using separate volume controls for each input. I think this is a good idea to match outputs from different sources.
2- DPDT switch to select between outputs. Again, a good idea rather than straight mixing them together (to prevent noise from the unused channel contaminating the output). But, the are not completely isolated. The two 10M resistors are there to prevent pop when switching. You do not want a pop right in your ears! A fancier version might include some kind of transistor based switching instead but that's getting complicated.

The only thing to spend money on here is a couple high quality op-amps. Maybe two of the Burr Brown or TLC2272 or something. TL072 might be fine...lower noise is the best option, though.

I think you could build this in a 1590B for about $30. But - this is just a draft. Whether or not it's perfect I dunno. It's only on paper now.