I have heard the Kemper and the Axe FX. Both are amazing signal processors, and they do an awful lot of things well. The Kemper in particular is in my humble estimation, THE state of the art for modeling.
But they have their limitations. So do real amps, of course, mainly weight and how loud they have to be.
I have a sampled grand piano that takes about 35 gigs of data, probably more data than is found in an amp model. It will fool you if you hear it over studio monitors. It will amaze you. It will trick you in a recorded track, if it's put in the right artificial reverb room, especially a reverb that uses impulse responses to model microphones, the room sound, etc.
But play a real piano next to it, and even recorded, and coming through over studio monitors, there is simply no comparison. That's because a real piano is a more nuanced thing to play, and to listen to, than even the finest sampled instrument. Playing is a feel thing, and a hearing thing, and a how it excites the sound in a room that is picked up by mics thing, and all that.
In any case, they both sound great, but the results are a bit different. As with amps v Kempers.
Same with sampled drums. And here, let's face it, it's awfully hard to hear a difference between a sampled drum and a
single real drum hit. But in a mix, the difference is easily heard, and very few bands actually record without a real person on drums. Why? Well, because we can hear the difference in a good mix. Part of it is the room, part of it is the limitation of the sampled medium, part is the feel the real player can put via nuanced approach to a real drum kit, and how that affects the emotion of the song, and the sound of the kit in the room, etc.
For me, the same is true of the Kemper and the Axe FX. They are great at their game, no doubt about it. But...a real amp feels and plays in a different way. I could easily justify owning one of these - it's less expensive than any of my real tube amps - I can't get fired up enough to do it. It's a great piece of gear, and yet it leaves me cold. But that's just my own take on it. Your mileage may vary, and obviously does, because we've both heard it and came away with different feelings.
Admittedly for me, the question often hinges on, "Is it inspiring to play through?" "Will I get excited about playing through it for years, the way I do with a good tube amp?"
I'll be interested in hearing your take on the Kemper when you get one, as I know you have very fine tube amps. I am curious not for the initial impression, but for what it's like to live with for a long period of time for you, i.e., will it stand the test of time?
I always cut important tracks with real amps.
When I have budget, I hire a real drummer, use a real bass, employ a real piano, book a larger studio to cut the drum tracks, etc. Often I don't have that kind of budget, since budgets for my kind of work have shrunk. But I think the stuff I cut with real drums sounds a hell of a lot better than stuff I cut with sampled instruments. A real B-3 simply slays a modeled one. A real piano matters.
However...
I doubt many of my clients can tell the difference, or care about it, but I can. As a musician and creator, I sometimes get depressed that what matters so much to me is unimportant to most folks.
In fact, thinking about it even now, I just want to throw in the towel, sit down in a corner, and have my guitar gently weep.
