Hello kirkus,
I doubt that the loadings used by B&O hung on to the 50/60s practices, particularly for the cartridges we are considering here. During the transition from multi-eq loadings to the generally accepted RIAA-standard, turntables/amplifiers had to accommodate a variety of EQ-standards. Many mono-recordings were using curves that differed significantly from RIAA, for instance.
But the Beogram 4000 came at a time when RIAA was well established, and when HiFi had begun moving away from giving users control of different curves. Soundsmith actually "beta-tested" different cartridges among selected customers, having given them different voicings, and the preference stated was for the brighter voicing.
As I theorize in my review, this could be because customers' vinyl had lost some treble, and the brighter voicing reintroduced it, or else because customers wanted a sound that more closely matched what they get from CDs.
A fun listening paradox is involved here. As you state, LPs became capable of reproducing better treble during the 60s/70s - but customers actually turned away from the best treble resolution available: DMM. They judged it harsh and bright, preferring the actually more muddled sound from pre-DMM vinyl reproduction. A conundrum for the conductors and performers, who found that DMM resulted in better treble than was available from any other record or tape method.
The classical music industry embraced DMM, but customers were skeptical, and as one by then couldn't adjust EQ-curves with any timing-specificity you were reduced to coarse treble/bass adjustments to get it to your liking. I have a complete Wagner Ring on Teldec DMM, an absolutely fantastic reproduction on vinyl, and it bombed when it was released.
Ironically, DMM-mastering is now all the vogue again in vinyl, and delivering even better results because of computer control in cutting.
Why did my Soundsmith SMMC20/CL+ cartridge sound fatiguing when reproducing Linn's Messiah? Well, the vinyl is very well made and has ample treble information. The brighter voicing of the cartridge overemphasized this, most likely.
I'm presently planning my next listening room, where I will have one of these. It gives me complete control of the EQ-curves and loadings, in an analogue signal chain. And everything comes full circle!
http://www.emt-studiotechnik.de/JPA66%20E.htm
