I received an answer from Lundahl regarding the LL1663 PPZ.
The first part of the answer is just confirming that this OPT is the right one for this application.
But the second part is rather ... hhhmmm ... you decide for yourself:
> If it is not asking too much, could you please describe the differences of the
> amorphous core to a mu-metal core.
> I have heard the amorphous core has the edge, but it is not clear to me why and
> how....
LL1663 is available with amorphous core or with SILICON IRON core. It is not available with mu metal core.
Difference between amorphous core and silicon iron core is a question of taste. I am afraid I am not an audiophile, so I can not comment on this difference. I am not even sure I hear it. But in spite of the high price we sell a fair number of amorphous core transformers, so I expect there is some truth to the difference...
Sorry I can not be more helpful.
- Per Lundahl
Of course I can't be sure of a lot of things.
May be he heard them in a PP amp for which this OPT was originally designed for, and which is a different story altogether.
But if I come back to my original question, I find that the situation just got worse.
In the beginning I had two to choose from, and now I have three...
To borrow from PJ: A Lotus, a Corvette and a Königsegg.
But are they really any better than a Ford is?
I actually do drive a Ford, and am very happy with it.
Now jokes aside, currently I am kinda drifting from the initial cluelessness towards utter confusion...