I have been doing a lot of research on Kemper, Axe Fx, Line6 Helix in terms of what amplifier and speakers do Kemper, Fractal Audio and Line6 recommend you should use.
Full Range Flat Response FRFR, speakers and amplifiers are recommended. Why because to reproduce the amp and cabinet model / profile you need the full range. If you use a guitar amp / speaker it will be coloured by the valves and cones of those, plus a normal guitar amp goes to about 5k and starts higher hence cannot take on a bass guitar well.
So studio monitors are fine through your DAW where you will get the actual sounds the vendors are wanting you to here for practicing and recording.
This means any guitar amp or speaker you have you will not use with these modellers / profilers.
So what is recommended for on stage or in live situations:
Atomic CLR, Mission Engineering Gemini 1 and 2, Matrix, Yamaha DXR, JBL EON, Friedman ASM12 etc
These are all monitors, some wedges and
Others to be considered Laney IRTX
Kemper and Fractal Audio initialling went after the DAW market and have added products for live use, but added is the word. Kemper really have added a pedal and an amp, but are reliant on 3rd party passive speakers! FA have done nothing this area in terms of amp or speakers.
And then there is Line6 who are going full bore into the amplifiers for this to replace your standard amp. Amplifi and the Firehawk 1500. And of course these can be used as a full acoustic amp as much as pickup guitar. The Firehawk 1500 is a tremendous replacement for your traditional valve areas, highly controllable. Plus you can use the Helix through the Firehawk 1500 for wet dry models in the Helix. Will they actually bring out a Helix 1500? The other thing is these amps are all bluetooth controllable from an iPad or PC. Very user friendly you can select amps, cabinets, pedals.
A bungle of questions arise:
Do these actually allow dynamics when you turn the guitar volume down, picking strength, feedback, thump, that awesome moving air of bigger speaker cabs?
Can you run your pedal board through these and how will they react?
Well the Kemper does, but I have not heard that questions answered for the others as yet. My expectation is they will. FA is definitely less user friendly and you need to use the PC interface for each of use, their pedals are not so easy to use and are work in progress. Line6 is definitely the most easiest.
Positive Grid Bias have produced an amp no speaker and just recommend a standard 8/16ohm cab for its 600w, which I think is not helpful. However, FRFR is what is designed for so if you want true model reproduction you will need one of third parties above.
Interesting Positive Grid are bringing out a modelling overdrive/distortion pedal so you can load up your favourite pedals into it and use with a standard valve set up. A new platform and very interesting.
So where next. Well fro smaller live full models you need the products like Line6 Firehawk 1500. The cost is a la the same as a mid range valve combo £850 as this is written. Kemper with amp is £1720 with passive speaker £500 to £600 plus £450 for the controller. Fractal Audio AX8 is £1100. So Line6 is the cheapest modeller with a complete amp set up. It also runs a complete wet dry and stereo capability saves having two or in my case 3 amps!
So you can take your studio sounds to the stage in stereo, not have a huge variation based on your settings of your valve and pedal set up.
I am now thinking of downsizing everything to the Line6 Firehawk 1500 and controller, but I am going to wait a year to see if Helix model comes out or whether the other vendors will also compete. Remember Yamaha is behind Line6 now and I see that as a way to increase R&D. When I went to look more closely the 1500 weighs 63lbs much more than my valve set up and pedals, so it got crossed off the list.
Since getting to the last paragraph I have discovered Blackstar ID Core Stereo, Boss Katana and Waza, Line6 Spider V all producing FRFR speakers and solid state modelling amps to different degrees at a mid range price for true 100watts. So not only are the modelling only people providing modellers, but the amp manufacturers too!