If they do have an analog output of the surround then yes you can plug them in directly. What you are looking for is 6 RCA connections on the bacl panel labelled Front Left, Front Right, Centre, Subwoofer, Rear Left, Rear Right. You hook your speakers directly to these ports.
If they don't u will need an AV reciever ($$) to do the job, and those usually amplify too, so you can get rid of the amp if you have one already.
My ALDI model had the Analog Surround Out. (Tevion DVD Recorder - MD 686x)