I figure this might be helpful for folks:
Real Amp vs TONEX vs Kemper vs Quad Cortex Comparison.
A pretty detailed analysis and A/B between a recording of a real amp alongside three profiles generated from the same amp/mic setup by TONEX, Kemper, and Neural DSP, although it's just one specific tone/gain level being examined. The really fascinating section for me was toward the end with the null test. For anyone not familiar, null tests are used by engineers to check how close two signals are to each other. You flip the phase of one and play both signals at unity gain, and see what is left over from the constructive and destructive interference. If the signals are identical, they null perfectly and you get silence. The more you can hear, the bigger the difference between the two signals, and whatever frequencies you hear are the ones that are different. So if you hear only high end in the null test, it means the lows and mids are identical but the highs are not, and so on. The TONEX was by far the closest on his null test.
A few thoughts as a former Kemper user: Profiling has its pros and cons. My AxeFX lets me adjust things like tone knobs and have them respond the way the real amp would. My Kemper's tone knobs were essentially post-processing; the profile is generated based on a snapshot of an amp with whatever settings were used at the time.
This became sort of a deal-breaker for me as an Offset user. I found that most amps were profiled by people using "the classics" - a Les Paul with PAFs or P90s, a Strat, or a Tele. The settings on the real amps that flatter those guitars weren't necessarily the ones that flattered
my guitars. I used the Kemper quite happily for a few years, but I hated it for the first couple of months because I couldn't get anything to sound right.
I eventually found just a couple of profiles that really clicked with my JM and Jag, and then
every tone I used was "post-processed" from that same profile that I generated using the profile editor (decreased gain, increased gain, decreased sharpness, increased pick attack, stuff like that).
TONEX seems to operate on the same principles, so I'd expect similar caveats. If you use "common" guitar setups, you'll find people who profiled amps that fit your guitars quite well. If you use weird guitars (like my G&L Z-coil Mustang), it'll probably take a fair bit of clicking through shitty-sounding profiles before you find something that really works.
That's a very different workflow from something like the Universal Audio unit, which takes the AxeFX-style approach of modeling all control interactions realistically. If you get the Blackface UA pedal, and your guitar sounds good through a real Blackface Fender, then you'll be able to twiddle the knobs and find those tones in there.
But if you use a TONEX profile (or whatever they call their patches, maybe the word "profile" is a Kemper trademark or something) based on a Blackface Deluxe, and the person capturing the profile cranked the treble to 8 because that's what they liked on their Goldtop LP, then you're getting a Blackface Deluxe with the treble set to 8, and maybe you only like that amp with the treble set to 3 or 4. A great example of this would be the Vox AC30, whose tone controls are interactive. The specific tones you get by playing with the treble and bass knobs will never be modelled by a profile, so you need to download one made with settings as close as possible to what you'd choose for your guitar.
The big advantage, though, is that you can create your own DIY profiles (if you have adequate gear and knowledge to set up the recording chain required). So, if you have a beloved amp with specific mods, speakers or settings you can't live without, you can capture them and enjoy the flexibility of going DI/reamping/saving patches/saving weight/etc.
They really offer a different user experience compared to the "analog modeling" approach. If you're not interested in capturing your own profiles, you need to be ready to just download/click through/audition a very large number of profiles to find the ones you like best. Each one is kinda like rolling up to some stranger's amp setup, plugging your guitar in, and not being allowed to fiddle with any knobs.
That's a bit of an exaggeration, because of course the modeler does have things like gain, treble, mid and bass knobs, but those alter the gain entering the model and the EQ of the pre- and post-model signal rather than what's happening inside the model itself, and tend to sound best in my experience when making modest corrections (same as when dealing with a recorded guitar track, really).
Just something to think about, because one approach might appeal more to you than the other. Profiles basically either sound good to you or don't, and require more auditioning but less deep editing. Analog models are far more malleable, which means less downloading and clicking through patches, but more time twisting knobs and/or diving into menus trying to get it to sound right.
The artist formerly known as mbene085.
