Well, I did as Rushton suggested and emailed Grado Labs. Their response to the fact that the gain on the phono in through the Statement Sonata/PH1 is disproportionately low compared to any other input was "That is normal with this cartridge. Please enjoy." Somehow less than satisfying. Based on that, I'd say 56 dB is not enough gain.
hrmph.
hrmph.