Line out into a power amp

Just got a grandmeister 36 and anybody know if you can run the line out to a power amp and not be hooked up to a cab. I think you can with the red box but I'm wanting to go into a power amp and the power amp is going into 2 cabs, I'm also using a atomic amplifire 12 into the power amp and wanting to run both at the same time for a wall of sound.any help would be appreciated
Thank you

I'm not too sure what you mean by some of this but let's give it a go.

Yes, you can take the Line Out to a second power amp as long as the GM36 is set to Silent on the Power Soak, (that's the speaker with the cross over it). That way the GM36's power amp has a load attached internally so is safe from damage. Of course that way the second part of your question would not work as the power amp is then set to silent. This works safely if this is all you want to do.

The Redbox may not be the thing to use for that job because it takes its signal from after the internal power amp and its output transformer. The Preamp Line Out takes its signal from before the Power Amp section. If you are getting the second power amp's signal shaping then you probably don't want the GM36's before it. Only use the Redbox when you want to model the GM36's power amp and transformer and a speaker cabinet response. It is mainly for feeding into flat amplifiers like a PA for front of house say. If you are feeding your signal into another guitar type power amp then use the Preamp Line Out. For the record, taking a signal out of the Preamp Line Out does not cut out the signal internally through the rest of the amp. It is simply another separately buffered output at the end of the Preamp chain.

Now to the alternative bit. Do you mean you are putting your Atomic Amplifire 12 into the Fx Loop, taking its input from the GM36 Loop Send and feeding it back into the GM36 Loop Return? That might seem a daft question but I wanted to be clear whether you are running the Amplifire into the GM36 Loop Return but feeding it direct from something else, maybe with some sort of splitting on the guitar signal. Plugging something external into the Loop Return should cut the GM36 Preamp internal signal and allow your external signal to take over. This way you would not want the Power Soak set to Silent as you want to use the Power Amp to actually make some noise. Changing the Power Soak settings will alter only the Amplifire level and not the Preamp Line Out level, that would be controlled from the other amp. (I don't know the Amplifire at all so have no idea of any fine details of how you would best be using it.)

It sounds like you want to run the Preamp Line Out into another amp and cab and at the same time, either run the Amplifire fully in the GM36 Fx Loop or feed it direct from the guitar and run it into the GM36 Loop Return. If that's what you mean then it is perfectly feasible as far as I can see.

I'm running my line out to a Marshall 8008 into a pair of v30s in the bottom of two 2X12. GB25s on the top for the amp. It really fills out the low end and adds dynamics. Watch that presence knob though. Turn it all the way down and bring it up slowly until you hear what you want. The label on that knob should be 0-100.