Eela Audio S120 Technical manual.
Comes in 4 parts as pdf file, right click to save:
S120 text file, description, adjustments,
S120 diagrams part 1, Input modules: S121, S122, S123.
S120 diagrams part 2, output modules, S124, S125, S126, S127, S128, general diagrams
EA902 power supply.
Please note: The S120 is manufactured over a long period, several versions do exist.