you will probably need to have the preamp on your interface turned up high and also have the vol on your amp up as SM57s (being dynamics) are not very sensitive. Also you will probably spend quite a lot of time finding the sweet spot for the mic. Start with the mic on axis (i.e. pointing straight) at the top right edge of the speaker cone, as close in as you can get and adjust form their.
My instructors page and www.studiotrax.net for all things recording.
my toons Brought to you by Dr BadGAS
my toons Brought to you by Dr BadGAS