Question about Sufficient Gain for LO MC

I have a question about how much gain is needed in a phono stage to be able to use a low output cartridge, like a .25 or .3 mv output cart. Would 63 db of gain in the phono stage/step-up be enough gain? I realize this will depend also on the line stage, the power amp and speakers, but I am just trying to get a general idea before spending any money. thanks.
I used a 0.27mv output cartridge before the one I have now, and it was just perfect with 66db gain in the phono section and 20db in the linestage. But I have a very low input sensitivity on my amp of only 0.3v for max output.

If your amp is fairly low on input sensitivity, and you have a reasonably high gain preamp with 20db or more, you will be just fine with that gain for those cartridges.

How is the correct gain calculated? Do you simply add the gain from the line stage to the phono stage for the total? What does the input sensitivity of the amp have to do with the calculation?
Yes, you just add up all the gains from the phono stage, line stage, and step up device( if there is one), and you have the total gain.

The reason why the amp sensitivity is important, is that the output of the preamp will be a certain voltage, depending upon the gain of the signal coming out of it. With a lower input sensitivity, the amp can reach full output levels with less output from the preamp, hence less gain needed. A low sensitivity like my amp(.3v) would need less ouput from the preamp than another amp that would need 2 volts to reach maximum output level.