Description

What to say... You will never get a chance to buy those ultra rare Sanken transistors, especially as NOS, NEVER USED!!!
One pair of rare Sanken transistors 2SA1068N / 2SC2493 for Sansui AU-X1!

2SA1068, 2SC2493 Sansui used in High Speed Premium Amplifier, model AU-X1, but you can find them at Sansui  AU-D907 Limited  too, so they could be perfect choice for power output of AU919 (because  AU-D907 Limited  is Japan domestic model but it is the same as AU 919)

Look at the picture taken from Sansui catalogue for AU-X1

Those Sanken transistors are high speed transistors, for example 2SC2493 has fT 70MHz (!) and Cob is only 100pF!! So, you can't find today production of TO3 power transistors with that speed.

fT number means frequency of transistor where the hfe = 1,  so those transistor are the first option (and maybe the only one option today!) for your high speed audio amplifier, if you wish to keep original slew rate, and that is very important for high speed audio amplifier such us Sansui AU-X1