Unfortunately, I have to let one of these units go to recover some funds and it's a very hard decision. I'll run down a list of things I've learned, and I'd like to hear some honest opinions from experienced users to help my decision. I love both units, but have my own unique needs, so this is not at all a 'this is better than the other' kind of thing.
* The AX8 has more lush, sparkling, dimensional clean tones as far as I can tell. The Kemper clean tones are outstanding as well, but the cleans sound warmer and more straightforward.
* The AX8 has a more solid sounding signal, but the Kemper has this kind of natural, organic transparency that is also very appealing.
* Both are awesome for metal, rock, and blues. The cleans are where they set apart a bit as mentioned.
* Rig manager is great, and the Kemper is so easy to use, but there are some things I wish I could tweak with some software. The Fractal software is great, but kind of annoying that it will not fit the screen of my computer (Come to think of it, the Two-Notes software is the same way).
* The ability to use different cabs is an obvious advantage of the Fractal. Some of the Kemper profiles do benefit from using cabs of other profiles, but it's still like putting a cab on a cab.
* The BIG LETDOWN from both units that I really miss from my Axe FXII XL+ is the USB audio feature. It was so nice being able to plug directly into my laptop using Audacity to record. It sucks having to have a separate interface with even more cables to manage.
* Kemper has the headphone jack which is very convenient. The AX8 doesn't, for whatever reason, even though it shouldn't have been a big deal to include one. For quick practice, I like to use some powered computer speakers instead of headphones. This also works on the AX8, but only mono (one speaker sounding) without the adapter cables to do stereo.
* Using studio monitors, powered computer speakers, power amp/amp FX return, and a powered PA, the distortion and clean tones of both units sound very similar. It's hard to tell different amps apart. However, the Kemper seems to have a little more uniqueness across rigs using this setup. Where both units are most outstanding is recording through an audio interface. That's where all the glory of each amp shines.
* I've used a few overdrives and distortions at the input of both units (Klon, TS808, Waza SD-1). The AX8 seems to be a little better at letting overdrive pedals influence the sound. The Kemper is awesome in that regard too, but it's almost like the Kemper's own sound is a bit more dominant. Still, it's just nuance and nothing really of note.
* Kemper has the most natural, amp-like feel between the two units. The AX8 has a more precise pick attack. I tried setting the pick, compression, etc... features of the Kemper, but they don't influence the feel as much as some of the settings Fractal allows. Having said that, the Kemper has the most variation of feel between amp profiles. Fractal has a little more grit, and that can be heard very well with the neck pickup. Kemper has kind of a squashy pick sound. I like it, especially when shredding, but it seems to have that on all profiles that use distortion. The Fractal is more varied between amps, so in that regard, a bit more realistic.
* I would say that there is a very slight edge given to the Kemper as far as being natural, authentic tone, but that mostly applies to anything audible. In direct recordings, I think the Kemper is still slightly more authentic than many of the Fractal patches - playing gained out metal, it's B.S. to say one can beat the other in authenticity as far as I'm concerned.
* EFFECTS - Well this always seems like a contentious point in discussions. I'll remain rather neutral because I like both. However, I'll say that I think the Fractal effects are better overall (and more of them). Kemper effects are very analog sounding in my opinion; very warm, sometimes muddy. Fractal effects can also be warm, but they're crystal clear, shimmery, and add some dimension to the sound. I do find on the Kemper that there is a very fine line where you can dial in exactly the amount of effect you need without getting too washy or muddy. It seems like the same limitation of how much you can tweak profiles from the way they were originally profiled also applies to how good the effects sound to whatever degree. Being that I'm not heavy into effects and only use them to add depth and dimension, or to play covers that require them, the Kemper gives me all that I need.
* Volume Levels - There are obviously variations on volume levels between patches on the Fractal stuff, but to be honest, the Kemper profiles vary wildly. As far as I can tell, the profiles that are very low volume in relation to all the other profiles do not sound good. By the time I get the gain and rig volume up enough to where it sounds loud and full enough, they lose something. I guess that is a result of how they were profiled. In any case, it would be nice to be able to level the rigs out a bit easier across the board. Maybe that feature is there, but I don't know as I'm still kind of new to Kemper.
* SUPPORT - OK, both Kemper and Fractal have great support. I think the Kemper forum is generally friendlier. The Fractal forum tends to have a lot of trolls that make it unfriendly for people just looking for support. Having said that, Fractal moderators do seem to try and keep their forums clean. As far as I can tell, Kemper's forum is pretty damned good.
Basically at this point, I'm liking the Kemper tonally, but leaning towards keeping the AX8 for the following reasons: it's smaller, has the footswitch built in, and would be also be usefful for using just the effects through my tube amp. However, every time I think about letting my Kemper go, I feel attached to it somehow.- for reasons I can't describe or even pinpoint. I just like it as much as the Fractal. Anyway, I've got to let one of these babies go, so I'm hoping someone can shine some light or offer another perspective to help me make this decision. Thanks in advance for your help.