pass aleph L preamp service manual

I think that everything is okay with the manual, of course the input impedance is quite low, but not really a problem for normal sources.
In passive mode you have some impedance in series to the source and i imagine that Nelson wanted to keep it as low as possible, because it increases the output impedance of the aleph L and it will ad to the output impedance of the source.
When i made the aleph L i found out that my CD player always sounded better in passive mode, and my phonostage always sounded better in active mode, independent from the level, so i put in a switch just to change the input from active to passive and i´m happy with the aleph L since then.
What i always hear with every preamp, is that the sound is changing with the input impedance just like a moving coil cartridge, so i just try it out which is the right impedance for each source.
But im not shure if its the sound of the source or the sound of the preamp that is changing.