A couple of month past since I restored my Technics SE-9600, but I haven’t shown any measurements yet. This is partly because I didn’t have an audio analyzer when I started the restoration. Now I do, but at the time I took the measurements, my test setup wasn’t good at all, resulting in really high THD+N figures. So you’ll get the THD (without noise) numbers as calculated by the QA403 audio analyzer. Actual results could be better than what is shown.
The SE-9600 doesn’t have any issue at all to reach it specified output power of 110W into 8 Ohm. At 1 kHz I measured a THD of just below 0.012%. At 1W this value dropped to 0.005% to 0.006%. The distortion levels are significantly higher at 20 kHz though, which is not a huge surprise. Still, the amplifier stayed well below the specified 0.08% (although Technics could have done a better job describing the condition for which the specification is valid).
At some point I should revisit this amp and see whether the the distortion could be lowered by increasing the bias a bit - to me the factory spec seems quite low.
Also, I wonder how the original boards perform. (For the driver boards I provisioned through holes that should make it pretty simple to use the original transistors.) Still, some slight changes may also come from the slightly different PCB layout, possibly requiring some adjustments to the compensation.
Either way, restoring this amp was a ton of fun for me. It worked out quite well considering I didn’t have to redo any of the PCBs; and the mechanical aspects like board outline, board edge connectors, mounting holes and so on are spot on. (That being said I made some changes/improvements to the schematic and layout just for fun - as mentioned before, but never ordered new PCBs.)