As mdalton stated, "you want to get the gain right". Critical to achieve that. If the cartridge manufacturer specifications state 60db, that may vary slightly one way or another and if your phono preamp does not allow a little leeway one way or another, you are limited with your settings.
To give you an idea, the Rega Ania setting recommended is 69.5db. That is a setting that few phono preamps can offer. I think maybe the actual 69.5 setting is one that only a Rega preamp can achieve. But Rega does things in a proprietary manner. Most LOMC cartridges will be in the low to mid-60's. Kind of shocked that the McIntosh only goes up to 60db. Maybe someone can explain that?
The Blue Unami would require around a 65db setting, so you would be better suited to figure out (for sure) what cartridge you will be using before buying a preamp.

