Are you not able to have different AMPS within the same scene?
No you cant run 2 amps within the same scene with the AX8 (you can with the Axe Fx II & III)
Think of a scene as a preset within a preset, although it goes a little deeper what you are basically doing is turning blocks on and off. Instead of selecting another preset or doing some tap dancing. This includes the blocks X/Y states
However!!! you can have two amp models available within the same preset (but you cant run both at the same time)
This is done in the form of X & Y as mentioned above, so X might be a clean Fender and Y might be Marshal.
Through scenes you can select which one you want so ___
scene 1 Fender, scene 2 Fender, Scene 3 Marshall, Scene 4 Marshall and so on, and don't forget all the effects you are turning on and off per scene.
Don't take this the wrong way, if you struggling use another rig tonight (way less pressure and you wont come to hate the unit)
Once you get your head wrapped around the units capabilities and get a workflow going, pretty sure you will love it.
The Fractal stuff come to think of it any processor is not really plug and play there is a curve, not like EQ-ing a amp and rolling with it.
Something that just occurred to me, if you have not used your AX-8 with at least 1 band rehearsal, I would really recommend using something else for tonight.