Using old pc as an 7.1ch audio reciever?

[RyuFlynn]

I have an excess of 5.1 ch surround sound speaker systems with dead receivers and old motherboards. My question is can i use and HDMI Passthrough device (such as a EL Gato) Intercept the audio and use this as my 7.1 or even 10.1 receiver? I have 2 old Sound Blaster Audigy 2 Z5's. I understand I may need some amplifiers but i have an old Sony-matic reel-reel player that is beyond repair but the case is in good shape, and i have the supplies and materials to build a 5 channel amplifier with 2 inputs and outputs per channel. A good 5.1 channel receiver is out of my price range. I already have a Older el gato that has issues when trying to stream video but always had good audio.