I have a collection of the old Quadraphonic records. I have not had the equipment to decode them for playback for many, many years. I was looking at what they are getting for used decoders on ebay and the price is just to high. A PC should be able to do a much better job anyway given the much greater computational power they have, all that would be needed is the software to do it. I found the answer here:
The reports are the sound is much better then anything the old matrix decoders could render.