What's up with picofarads?

What sonic differences generally occur by changing the MM picofarad (pF) settings of a phono section. My Pass Aleph Ono allows "none," 100pF, 220pF or 330pF and allows any combination of the three totalling 650 pF (plus 2 DIY custom settings). I really can't detect any difference from one to the other. I'm using a Sumiko SHO cartridge on the MM setting.
The SHO is a moving coil, and isn't sensitive to capacitance like a MM cartridge is. MC's are more sensitive to impedance. As long as the input is set at the right impedance, forget the pF settings!
Many MC's are affected by the capacitance that they load into. The fact that your cartridge doesn't seem to be "bothered" by any of the settings tells me that it is probably less sensitive to capacive loading. You might want to experiment with the resistance of the load though as this surely WILL alter frequency response. Sean
Sean makes ther point that capacitance CAN effect a MC, it's just that most of them don't seem to be as effected by these small changes in value as a MM is. If you don't hear the difference don't sweat it.

The original ARC SP 9 came with a 560pF cap in the loading section to prevent instability with some high output moving coils. My Shinnon Red sounded better without it and didn't cause any ossilation.

The SHO is designed to sound good into a MM phono set up for a load of 47K ohms if I remember right. It seems to me like you are pretty good to go with the Pass and this cartridge. I always wanted to try one, how do you like the sound of the SHO so far? I was a big far of the Virtuoso Boron which was the previous Sumiko offering. Anyone out there know anything about the sound of the new Sumiko Blackbird? That might be my next cartridge judging from what I have been able to dig up so far.
My SHO is seven years old. It runs in an SME IV.vi arm on a SOTA Star upgraded to NOVA back when. I have been very happy with it feeding an Aragon 47k all these years. But I just gave the 47k to my son for his analog setup...and got the Pass Ono from this website last week. I'm hearing some deep details and air I never heard before along with snappier bass, but singing voices seem just a bit receeded from what I remember with the 47k. Too soon for definitive evaluation.

Anyway, I've been checking out the classified here for a new or low mileage Ruby 2 or Helikon...and have come across all the raves for the Shelter 901, which I'd never heard of before. I think I want one immediately! Any more opinions or hearsay about this item?