Hey Raul,
I know heaps, I've forgotten heaps and I'm sure there is always opportunity to learn more. What's wrong with thanking someone for putting time and effort into explaining their experiences.
By the way with regard to the RIAA curve, since you are a manufacturer of phono stages, the comments I made on an earlier other thread were slightly askew. The RIAA standards require amplifiers that drive the cutterheads to apply compression and expansion above and below 1000hz. The engineers could not build amplifiers in those days to do that and In actual fact you will find the turnover points are actually around 400hz and ( I cant remember the figure ) but around 4000hz. This means for accurate reproduction of RIAA recordings you actually need a flat midrange at around 400hz to 4khz.
As stated earlier I have a mathemetician/engineer mate who has modelled this revised RIAA playback in an op amp based phono stage ( not your normal stuff, the op amps used are next generation designs not yet available to manufacturers ) and the organic wholeness of the midrange is revelatory.
Ironically you could drive the cutterheads far more accurately today as regards RIAA compression/expansion with digital amps.
Cheers,