Are we all forgetting distortion from the speaker simulated circuit ?
PA speakers are not guitar speakers so add the speaker breakup like a guitar speaker is the reason i presume for the simulation.
No i think i wont give you what you expect,.
The impedence question can only be answered by trying it !
I thought you should be prepared for less than a clean sound,distortion may seem muddy and lifeless or nasal shrill sounding if the impedence is way off.
Im curious and hope it works well but i see much im cautious about so temper optimizium.
I say try it with amp DI out sending at a low volume at first because that amp is the master volume of both amps now
and the recieving amp starts a full volume.
The Rebel DI output varies with the master volume control so does the cube do the same ?
GOOD LUCK TOO YA