If the Shelter 901 sounds over the top in your system, how do you think it would sound in mine? I will have to pass on this cartridge. Did different loadings have any effect? Did you try a lower resistance setting to try to soften the top end?Yes, I've tried quite fine impedance adjustments. Our stepup tranniess have resistor terminals built in, so I can change cartridge loading in a few seconds to any value I choose. With the 901 we tried values from 19 ohms to 50 before settling on 38. This was with a HIFI modded OL Silver. When we changed arms the optimal load for the 901 changed to 37.5 ohms, no doubt due a slight difference in arm cables.
For the ZYX Airy, I started at 10 ohms, because this gives a similar ratio of impedance load to internal cartridge impedance as 38 ohms does for a Shelter 901. This seems to be pretty nearly ideal in our system.
The slight brightness or etched-ness of the 901 cannot be tamed by loading it down, unless you suppress the highs altogether I suppose. We heard it through Cello's Supratek Cortese at 500, 100 and 50 ohms. It's audible in my very different system at any listenable load. As Soliver says, it's just in the nature of the cartridge. It's a kind of ringing or resonance that causes the 901 to slightly over-emphasise detail and surface noise, and throws everything to the front. The ZYX lets truly quiet passages play as soft as a mouse. The 901 doesn't know how to do that.