I have several computers that I plug into a stereo. With it, I can select which computer I want to listen to. But the thing is, I want to be able to listen to them all at once. There are audio mixers out there that will combine inputs, but they all involve studio mixing, which has far more functionality (and therefore cost) than I want to spend. How I can listen to multiple audio sources at once from one stereo? Daisy chaining has been one solution so far, but it's cumbersome and needlessly complex for what should be a simple task.
My Immediate suggestion would be to look at one of Behringer's XENYX options, the 502, 802 or 1002 .
these mixers are 5, 8 and 10 channel respectively and 35, 55 and 57 GBP respectively. the links are below (I could only post two links,???)
If these options are too expensive then maybe you could provide a budget?? You also may need some extra wires with these as they take full sized aux cables (not xlr or 3.5 mm, you could use a 3.5 to full size adapter if that suits you better)
I know you said that these things have more functionality than you need, but at that price you can't really go wrong. it's very cheap for the actual hardware you are receiving. you may possibly need the extra tonal functionality at a later stage anyway, or if you want to add a little bit of bass to one of the lines!