yep, just run line out from your sound card to rca in on a receiver/amp. I've never run to a mixer before, so I don't know that one.
But for a receiver/amp you just run rca-in and then speakers hook to the speaker terminals on that as well. The receiver/amp has volume knob and whatnot. They pretty much do the same thing though. A receiver usually has multiple ins and radio as well.
As for wireless, I don't know, I'm sure there's something though.