So the options are "input block" Volume, "amp block" volume, and "output block" which is not an option that "should be used" to raise the signal.
There are also physical knobs on the top, which are not connected to any of these controls.
My understanding was that the little knobs on the top, set to full, were "proper" or unity.
Thus they should always be set to max...
Yes "noise floor" is important etc.
So is not clipping obviously.
increasing the Input Block will change the level going INTO the amp block so it will be as if you turned your guitar up louder, ruining gain staging. same for turning it down. this is not the place to level a preset. with high gain sounds, the level probably will barely change.
Output block can be used, but if you change amp channels (or any other block changes volume drastically) you'd just have to adjust the Out block again, messing up the previous channel's setting.
the Amp block is typically the best place to adjust level because when used, it's the biggest source of volume. Drive/Gain, Master Volume, and many other settings in the Amp block change the volume drastically, so why not adjust it where that happens.
the Level parameter in the Amp block does NOT change tone. the resulting number for Level is not important, again because the other parameters in the Amp block change the level so drastically. for example, a Master Volume setting of 1 might cause Level to be -8 dB, where a MV setting of 10 could cause Level to be -20, way less. no sense to make those changes, then go to the Out block to adjust.
at a gig with a real amp, if you're too loud or quiet at sound check, what do you adjust? an EQ pedal in the loop? probably the Amp. same concept here, really.
Unity Gain means the level is same at the Input and Output. once you put a block that can change level so drastically like the Amp block, you're no longer at Unity Gain. so having the knobs all the way up
for that reason doesn't create unity.
it takes a lot of words to explain things via text. but the simple solution is to adjust the Amp block Level parameter.
that's why Amp Level appears in Edit's Preset Leveling function, and why previous generation Leveling functions had the Amp Level control there too. for the Axe3 generation, go to the Layout, Zoom out with the A knob, then view the meters at the top of the screen. Nav to highlight the Amp block, then turn the C knob to quickly adjust Amp level up or down.
situations where i wouldn't use Amp Level to adjust volume are presets where there's a compressor at the very end of the chain. adjusting Amp Level there would change how the compressor functions and change the tone. so first - without the compressor on - i'd level the Amp block like normal, then add the compressor and adjust as needed.
from there if i needed a level change, i'd adjust the compressor because the Amp Level is locked due to how the compressor works.