I had to wait til today to try to get those "Plexi" type tones with the Archon. The wife was gone so I had my chance. I cranked the master wide open and jacked up Presence, Treble and the mids, and turned Depth all the way down, Bass all the way down, etc. Oh, the gain... you should see the gain knob. It is probably sitting around 7:30! I mean it's very very close to all the way off! I turn it 1/8" and the amp goes quite. It's just barely up high enough to make sound.
I played for a few seconds and then dialed from there. By the end, I was at T dimed, P dimed, M to taste, liked it noon or above, B 9:00, D off, gain between the original spot and up as high as maybe 8:30. I'd say it's pretty close to the tones above. Very open, punchy, dynamic, bright, crunchy and due to the volume, the bottom end doesn't sound thin for that type tone. I was using V30s and feel it would have been even closer with greenbacks.
That's the good news. The bad news is, you just can't get those tones at lower volumes. Turn the volume down and the magic of that type tone goes away. This is because when you really push the back end, what you're hearing is PI distortion and power tube distortion, and not pre-amp distortion. When you turn the amp down, you lose the PI and Power tube distortion and the only way to get distortion back is add it at the pre-amp stage, and that is very different in sound and feel.
What Les said above makes perfect sense about choosing the 30 watt because it breaks up sooner. A 100 watter will have more bottom punch but can't get those gain levels at volumes that I could EVER get away with. So that magic is only available with lower wattage amps to most people. Knowing where the magic is with those type amps, I also wouldn't want even a 50 watter, unless there was no "big glass" option. Since the 30 is El34, that is the one I'd try if I ever tried one.