Best gain setting on phono pre- low/medium/high?

I have a phone preamp that permits three gain setting, 56dB, 66dB and 76dB. All three are usable, just need to adjust the volume on my preamp differently. What's the best thing to do- use lowest phono gain and more preamp gain, most phono gain and less preamp gain, or stick to the middle settings? 

I know this sounds like the 3 bears. 

I recall reading sometime back that keeping the volume control higher has advantages