Ok Just thought I'd add a few points to keep in mind before you get lost in the maze of teckno babble.
Ask yourselves this Q?
What do all these complex systems actually Do? Or; What do they All have in common?
If you are are like me and sick of getting lost with wordy advertizing brochures that claim to deliver some rare and unobtainable tone mojo you will eventually realize that almost all of these devices simply alter the friggin TONE.
I may never fully understand the vastly complex but I've been around the block a few times.
I've found from my many expeditions into this stuff it is actually a lot simpler to use more than one tone control system.
I very much doubt that ANY cab sim on it's own will instantly turn a Roland JC 120 into an ACDC concert. (and Yes I have met kids who actually believe that the acquisition of some brand name gizmo will do such things)
You build tone shapes, one shape imposed into the next stage which may have a completely different shape. Common logic tells one that the combinations are endless but there are some basic observations that can be made.
It has already been said by better minds than mine,,, read this; http://www.amptone.com/truesecretofamptone.htm
(all text and a bit wordy but the message is clear, to me at least)
Don't worry about the Load box Attenuator stuff ,,
just get into the Head space of what is happening with complex circuits.
**Pedals and such (on there own) don't and will likely never deliver stunning results.**
Every time you ADD something you have to Reset/Readjust the Tone shaping.
Notice my circuit path has; Input > HiZ Tone shaping before distortion > Then Dist > Cabsim >
*But it ALSO passes through a graphic before passing to > the main Amp.*
My graphic is simply an old unwanted Tandy branded hifi unit ,, cost me $8.
Adding the dedicated HiZ tone stack **BEFORE** distortion makes a massive massive difference to the control and feel of the distortion.
>>> Notice how nearly all the stomp boxes have any tone shaping **AFTER** dist circuitry???
If you already have a very good sound and you simply want to add cab sim for recording then you may have some luck with a dedicated sim but to my mind it does rather limit your options. Whereas I like to have access to a lot of different options.
Adding This also, It may help you understand how darn easy it is to loose the mojo.
If you run through digital stuff expect a lot of hi freq to be added even with cab sims. I do use DDelay but it runs on a side chain path so the original analog sound is never compromised.
The JTM Cam sim is very good (albeit a tad noisy with high gain stuff) but it does depend on where and how you use them.
i.e, The Cabsim in front of my old Quadraverb did little,,,(even useless) But inserted After Qverb reaped very impressive results.
I built and sold a few of those JTM boxes to some local recording geeks and One such chap commented;
"Man I'm in heaven, I never realized that too much bandwidth trashes good OD guitar tracks."
So yes Digital EFx might open doors but beware of the pitfalls.
Anyway toss it around.
Have fun, Phil.