hi Ron,
Are you talking of the OP's original circuit were he was trying to drive a LM386 directly from the emitter of the 4N25 or the modified circuit I posted.
If the former, I was explaining to the OP as the 4N25 had a emitter drive current of only ~20mA and the Transfer ration is only 20%, the 4N25 emitter would at best 'provide' ~5mA into the LM386.
That was the reason he measuring only ~5V at the 4N25 emitter with LM386 connected.
In the OP's 2nd circuit with the TIP120, this would act as current amplifier for the 5mA 4N25 emitter current, also I pointed out there would be voltage drop from the 12V to ~10.5V due to the Vbe drops.
As the 4N25 and TIP120 are configured as emitter followers the transistors would not saturate and be would as I posted, I have shown the 4N25/220R as 5V for the sim , which shows this result.
Perhaps I am misunderstanding your post.?
EDIT:
I 'think' you are referring to the Vce sat of the 4N25 transistor as the Base is 'floating', this is of course ~0.1V.
The LTS plot shows this.
I should have explained it more clearly to the OP, of course in his application its a minor problem.
E.