Headphone question..

Now, I'm fairly clueless when it comes to audio, and I've a question to ask before I run out and buy any cables or the like.

The situation is I've recently decided to hook up my PS3 to my computer monitor via HDMI, and I'm wondering how to best deal with the sound. As far as I see it, I have (possibly) two options here, at least that would accomplish what I desire. I'm hooked up to my PC at the moment via a pair of headphones, and I desire to still be able to receive my PC audio through these even while using the PS3. I was curious, however, if it is possible to receive output from both the PS3 (via the monitor's audio-out) and the PC at the same time (by using a splitter to plug the headphones into both my PC's sound card and the monitor's audio-out), or would that not function?

The other option I was thinking about was connecting my PS3's audio via optical to my PC's sound card, and hoping I'd be able to hear the audio from both the PC and PS3 that way...but I'm uncertain, too, if that would work, since I'm not sure if I'd have to switch between the PC and Optical-in for sound or not. Would this possibility work, or no..?

If neither is doable, I could always pick up some speakers and hook them up to my monitor's audio-out, but I'm curious first to see if I can get the sound from both PS3/monitor and my PC going to the same pair of headphones somehow (and simultaneously). =>

Edit: To mention hardware, or at least all that I think should matter, my sound card is unfortunately the original X-Fi XtremeGamer. Which means to use the second option (if it is possible), I'd need to use an optical adapter, I realize.

splitter thing: no don't do it it will cause a lot of trouble and not work

digital out from monitor to soundcard's digital in: yes do do it it will give you mixer control over the PS3 volume and accomplish exactly what you want

PS3 to PC via analog (use line-in port). You will need a 2xRCA to 3.5mm stereo adapter. Some versions will be easier to connect than others, i.e. you probably want the version that looks like this:



and not the one that looks like this:

Rummaged around, found a stereo plug hidden away in a drawer, and gave it a shot...and everything works perfectly. Now I can fool around playing my PS3 on my monitor while still conversing with friends in Ventrilo, and so on. Thanks muchly!