Connecting ancient Realistic STA-2280 stereo receiver to computer

[Garquill]

This used to belong to my dad. I'm wondering if I'd be able to connect it to my computers to play some large floor speakers or headphones through, or if it could be connected to my sound card with an amp (sound blaster z). I don't actually know what it is and have no way of directly sending music to it right now.
 
I know I can connect the bare wires from the speakers to the back, but to get the audio to the computer could I use male red/white rca cables from the receiver to male 3.5mm into the motherboard or sound card (is it redundant with the sound card?)
 
my motherboard has a SPDIF out and my sound card has an optical out (not sure of differences)
 


 
someone else's video of it
 

 

[flatmap]

The simplest way to connect, is to use a cable with the "male red/white rca" connectors on one end and a mini phono plug on the other end.  The rca's would go into either of the inputs marked for aux or into either of the Tape In inputs.  The mini phono plug would then go directly into the headphone socket on you computer.  I think that's the most straight forward. 
 
Here's an example cable, just so you can see what it looks like.  This is probably the most cheaply made cable possible  -- so you might want to spend a bit more and get something that will stand up over time.
 
You may find that the sound quality is not as good as you want or that there is too much noise along with the music.  In that case you may want to invest in a DAC, in order to bypass the the built-in DAC in your computer.  A sound card is basically a DAC plus amplifier.  You can also get external DACs that will plug into a usb port on the computer as well as via spdif or toslink.
 
But start with the cable....