Whats the best way to mic my guitar amp for recording in a studio/practice room?
I know you’re asking about how to mic your amp, but have you tried the XLR DI on the back of your amp? Line 6 has built their brand on tone emulation and easy home recording solutions, and they’ve thoughtfully put a DI there for just this purpose (I don’t know of any other tube guitar amp that does this). It’s worth trying — it might sound pretty good and it’s darn easy to set up. You could also try a mic on the speaker as well as the DI. Good luck!
One little trick that’s worked for me in the past: if your amp has an open back where the speaker is visible, try aiming a spare mic into the back of the amp. You get some deeper tones this way, and mixing this mic in with the ones pointed at the front of the amp can give you a wider range of sound.