I'll go a bit further with my explanation. To the audience somewhere in the middle and the back, the sound is identical. To the people right up front and especially for me, I grew up listening with my knees or something, because there's something I miss without the real speakers being pushed. I use the power amp and real speakers with one set of outputs, while the Main Outs go to FOH. That way, everyone is happy. And for me, it sounds every bit as good as my original tube amps, and I think better. I don't play with crushing distortion, so I need some space and tone in there. I cannot describe the technical elements that go into amp-in-the-room. But I sure know it when I sense it. And for an earlier post, I swear to god, the QSC is super heavy. And if you think that's bad, I use my vintage talk box, and therefore cart around an additional Crown, lol. Maybe, maybe, the FM3 will promise a small bit of weight reduction, but who knows. It's currently sitting on the floor like a puppy. I have the AF3 tuned in to several realms of heaven, and wish I could will the FM3 to program itself direct from the III.
Did I mention that the vintage speakers are a blend of two JLB AlNiCo D120Fs and a couple of equally fine ceramics? Holy immovable object, Batman! The only thing that makes it worthwhile, are the people that say, "Holy crap! That sounds exactly right!"