A preamp is good but you should get decent levels for really loud shows. For sound quality reasons you need to use line-in setting while recording, not mic-in (which severely rolls off the high frequencies). Run it at the maximum gain for line-in, which is +12 dB.
Also, is the microphone's internal battery still good (and did you switch the mic to 'batt on')? Your attempts with 48dB of gain on mic-in should have pushed your levels over the limit so something's not right here.