I'm now making experimnts to find best amp set up and very precise mic for live gigs. In my case best recording tones comes usually with mic on the cone and defult eq settings but there is no way I could stand that tone coming from the amp at stage volume level so now I work on getting best placement for high volume transpitions. I really hate what most popular guitar mics does with the treble.
What I mean is...I always set amp the guitar tone being exaclty at speakers height right in the face
I like to be sure people in front of the amp (in case of pub playing) don't get any harshness. but even if the tone is warm as hell (at high volume, of course it would be useless for recordings) I found that on the front speakers it still could be screwed. The biggest challenge here is how to get rid of treble (moving the mic off center) but at the same time not get too much bass.
One of the very popular situations on stage is to hear from the sound engeneer "man...roll down some bass" and the answer is..."man...it's already on zero!"
So the purpose of my experiments is to get compromise - nice tone on stage and well transmited on the front speakers.
By far what I can say is that the type of amps I like ( the RH30 for exmaple) has not a huge low end issues (much less lows on default position than some reference high gain amps) work best with 5 cm mic distance, off center (cone) and treble roll off to 25%. More or less doing this without any additional tweaking gives me acceptable toe for recordings (acceptable = refering to my taste)
But I could not stand that tone on stage (I mean....we hear different when the volume goes up) no the more "off center" I give the mic, i can still hear nasty 4-6 kHz boost but I loose some juicy high mids.
I had a few more ideas to make tons of another tests:
1. acoustic foam glues to the cabinet cloth only at the cap range - sort of natural LPF. This will provide best high mids, smallest low boost and overall....most even tone. But without a foam it's ugly as hell - even warm tone from the speaker, the mic treble boost destry it all...
2. SM57 mod - I found some german doing simple, passive circuit (a few coils, caps and pot) to flatten then natural 4-6 kHz boost of SM57. This could make me able to move the mic closer to the cap and again....get better translation between what I hear from the speaker and what the audience hear