It’s possible. Set the AX8 for 4CM as described in the manual. If there’s hum, use humbuster cables or a device such as the Morley Ebtech Hum Eliminator.
Put a loop block after the pre FX (such as Drive, Comp, etc) and before the post FX (Mod, Delay, Reverb). When the loop block is engaged, you get the preamp signal from your amp. When you (i.e. in another scene in your preset) disengage the loop block, but engage the amp block, you get the preamp from your AX8 running into the FX return of your amp. The only challenge is balancing the levels between the settings. Good luck!
