Well, normally I would talk shit at this point... but you get some killer tones so, expand.
What does your chain look like?
Do you pull tone from the FX send or the speaker out with a power soak?
What DIs do you use?
Convolution amp sim. or plugin amp sim.
Do you sample your own cabs?
guitar -> amp -> fx send -> direct box (great river, or any di box) -> interface
if you're looking to get the power stage in the tone, as opposed to only the pre stage, then yeah use a power soak, but i never have
and obviously you need the head hooked to a cab somewhere so you dont blow the head
i usually either use either the built in direct box on the mackie 800r, or the great river. great river will add that "iron" to the tone, because of its transformer, but this is not essential to doing this method. i did this method with a firepod for a long time before i got decent gear.
the plugin i use for the cab simulation is made by waves, its called waves gtr. you use the "2 cab mono" one, and you bypass the amp section. then you choose 2 seperate different cabs, and 2 different microphones (for mono amp channel). you get on axis and off axis choice placement, along with volume for each microphone serving as your "mix" persay. if you wanna get tricky, you can mess with the stereo versions of the 2 cab, by routing the mono input to a stereo track, and loading the stereo 2 cab plugin as an insert. you wont be able to record it this way, but you can always render later (with decent computer, you can monitor with low latency in nuendo). but this plugin puts a beating on your cpu when you get to 4 geetar tracks.
its really that simple, get your signal around -3 db into the interface, and then when you throw the cab sim on, you'll probably have to use the master out (turn down) to avoid clipping. bass is a bit touchy here, so make sure you really have it set how you want it on the amp, then go a tiny hair lower. seriously.
you'll get some fat tones (royer emulation is one of the mic choices), and the playing / sound with be very detailed and defined. and just like any real cab, you'll have to use a high and low pass filter during mix.
another trick is to do the same thing, but using a pod, and turning the cab sim off on the pod, and using the waves cab sim instead.
i dont mic guitar amps because a long time ago i tried on like, 15 different bands and had all bad tones. the day i started doing direct, things started sounding right to my ears. even though i have lots of label work, i dont really consider my self anything special. i just have my own methods that work well. maybe thats all that matters but, if i were to go into a big studio, im sure i'd be screwed when it came time to do guitars. haha. but then again, i dont have a lot of pre's to mess with.
