This baby came in for a recap and few mods....Most Maintainable build I think I have ever seen.  Its dream to work on. 

 I am getting interested in building a hardware stereo image widener circuit.  I have seen a few ideas floating around based on the Middle(M) +Side(S) technique.  The basic premise can be summarized into the following equations:

Encoding M and S

Middle  = L+R

Side  = L-R

Middle Circuit

Translating that into basic op-amp circuits, the Middle signal could be created with a summing amplifier.