Honashagen 5-26-2018
As I sit here listening with no preamp, it seems like common sense would tell you that if a preamp alters the sound from the source in any way it's really a processor of some type. Right?
... Unless, that is, the presence of the preamp somehow causes the source component to behave in a more accurate manner. And as you've read above, there are what I would consider to be plausible technical explanations for why that may be the case in some systems.
Also, my perception has been that in past threads in which the preamp/no preamp issue has been discussed a significant majority of the reported user experiences has been that the addition of an active preamp to the path between a source component containing a DAC and a power amp has been beneficial. I would not assume that all and perhaps even most of those experiences were the result of inaccuracies introduced by the preamp.
Subtle effects can often occur in electronic circuits and systems that have consequences which are counter-intuitive, and that are not necessarily consistent with what "common sense" may lead one to expect.
Regards,
-- Al