Not by the accounts I've explored... and I highly doubt it.
From my research, the original Matador is the model 611. I can't find any online schematics for that but, according to the Farfisa Heaven website, the Matador-R is identical other than the latter having a 1970s rhythm unit built in.
There are several sources for the Matador-R schematics online... and they show no valves! The Matador was an early1970s design, by which time silicon transistors and 74-series logic chops were standard. The schematics show a simple small transistor amp for the internal speakers/headphones.
The line-out comes direct from the preamp, from the same point that feeds the power amp. Since the latter clearly works it must be something pretty trivial that is stopping the line out from working.
There are 12 multivibe oscillators for each note in the top octave, with logic dividers for the other octaves. It looks like the organ combines multiple octave notes onto the keys across the middle of the keyboard, so the different perceived levels across octaves might be intentional.
