Cartridge Loading- Low output M/C

At 100 ohms...which gain setting would you use 60 db or 66 ?

My preamp has 60 db of gain for MC and seems adequate.  I would start there and see what ya think. 

Definitely try to stick to 60db gain if at all possible.
The higher the gain the more chance of inducing background noise, you know the hiss you can hear at the speakers with no record playing.
Good luck and trust your ears

In my experience, a very low resistive load, which puts a correspondingly heavy load on the cartridge, acts like a tone control, which is to say that as you approach the internal resistance of the cartridge itself, the treble is rolled off progressively and eventually some gain is lost to ground.  In theory, if the internal R of the Cadenza is 5 ohms, the minimum load resistance would be around 47 ohms, or 10X that of the cartridge, as someone else already suggested above. But I have lately found that even LOMC cartridges sound their best when the cartridge is essentially un-loaded, at 47K ohms.  The treble is more "open" and airy.  Dynamics are also improved vs more traditional values of load resistance.  (LOMCs with low internal resistance, like the Cadenza, are traditionally loaded with 100 ohms, a set it and forget it value.)  Ralph Karsten (Atma-sphere) points out that not all phono stages behave properly when LOMCs are presented with a 47K load, so maybe I am just lucky.  I agree with the person who said that the "best" choice is phono stage AND cartridge dependent.

Just to clarify:

A LOMC set at 47K ohms is technically and electronically NOT "unloaded". Granted it might not do much with it, but it’s still loaded at 47,000 ohms.

Rule of thumb, (as stated above) 10X the internal R is the best place to start.

Proper (or improper) loading of a cartridge will not change the "intrinsic" sonic characteristic of said cartridge.

Also, gain and loading are independent of each other. Always try the lowest gain setting to avoid noise, but choose whatever sounds best at the volume you listen to.