The awesomeness comes from (1) the cab/speakers and (2) head. If you manage to hammer this somewhere in your brain, the chain becomes easier. You will then realise that pure DI is just noise from the tone-aware perspective. Just the head, coupled with some capacitors and resistors. W T F? Exactly.
And also, (3) the room acoustics. A 4x12 array with the gain pumped up beyond 12 will shake the entire room/house, and all this energy contributes a huge part to the tone. It's the factor that makes it "thick".
So yes, you don't have the luxury of miking such beasts.
A guitar amp sim sw/hw, based on impulse responses, beats a 30-watter machiam like water. Why? Get this right. IRs are accurate reproductions of the characteristics of the room, head, cab and mic. And by accurate, I mean to the bit (duh?). This is where digital overpowers analogue by a milestone. I know GR 3's IRs are pretty comparable to the biggest combo amps, even when you do just 1 layer.
And please, don't use an amp sim hw like the pod and plug it in to your Roland 30 hoping it'll "beefen up". It won't - it totally ruins the purpose. Use cab simulation or not, you're miking the small thing in the end and not capturing the true output of the pod.
ReValver/Peavey's MK II (not sure about III) and IK's AmpliTube don't have that many amazing IR-based presets, but with MK II you can easily load up a solid IR file (freely distributed by awesome people) and do just 2 layers for that awesome chugga chugga.
For more awesomeness, join the fun @
www.guitarampmodeling.com