Simple Audio Volume Select with or without input select

I'm trying to connect my PC and Wii to the same set of speakers, however I've run into a few problems.
While the speakers are good, they are extremely loud, even at the lowest volume settings when using them with the Wii. Unfortunately, the Wii has no way to set Audio volume in it's OS (or I haven't found it, if you have I'd appreciate the help) and so I can't lower the volume enough to hear it without waking up my neighbors.

I was looking for something that will allow me to set the volume separately, so that before the audio gets to the speakers it's already toned down. If I could I'd like to get one with the ability to switch between inputs as well, that way I could switch from my PC to Wii without having to rewire each time, though I don't mind it that much. If anybody out there knows of a product that can do this please help me out, as it is I can't use my Wii with my speakers at all since they are just too loud. The main feature it needs to have to just the ability to set the volume between the Wii and the Speakers, hopefully without messing up the audio quality too much.

Thanks to anyone who reads this!