So i installed again the EPC-450CII on one of my turntables using the "ultra simple" preamp, but this time using a 31-band equalizer to dial in a preferred EQ.
Then i A/B compare the same record's sound using another turntable which is fitted with a Grado MCX low output cartridge (fitted with a Grado Red1 stylus) which IMHO has a very nice, appealing tonal balance. So this Grado is my "reference" for tonal balance. Plus it's sounding nice, nicer than i expected from a Grado.
Comparing both, i see that my EQ correction circuit (posted before) will not be so good. The "valley" reported in tests between 2-6KHz is IMHO necessary for perceiving the sound as "smooth". Such a "valley" appears in cartridges like the Grado Prestige line (i.e. Red) and the M97xE and i'm totally sure this is what gives them a "smooth" sound quality. My EQ correction circuit would flatten said valley, and now i'm convincing myself that this isn't so desirable.
On the other hand, the 250-650Hz range definitely benefits from a 2.5-3dB reduction. Deep bass could be enhanced too.
Finally, the 15-20KHz frequencies are way too loud with this cartridge. I think a low pass filter with cutoff frequency between 10 and 14KHz definitely helps a lot with the cymbals. I'm currently trying 12KHz with great results.
All in all, it seems i'll have to re-design the EQ circuit. Don't hate me
Good news is that this cartridge indeed is superior sounding...