If you plug a hardware preamp into a hardware power amp and cook the front end of the power amp, it's input gain stage doesn't shit the bed from being overdriven, even if you run the preamp hot as hell into it, or crank the treble.
The neutral tone stack isn't a neutral preamp, it's just a neutral tone stack dropped into the preamp of the loaded amp, the loaded amp's preamp and gain staging remains no matter what tonestack you use. Even using the cleanest possible tube amp, the top end gain staging still falls apart if it gets pushed, it's not neutral in any sense.
Even using an amp with the cleanest possible input gain staging, if it's a tube amp, the treble interaction form the cascading gain of the existing preamp gets messy af in the top and falls apart, a tube power amp doesn't have that extra cascading gain stage of an additional (remaining) preamp in front of it.
To hear what a pedal sounds like as an amp you have to use the JC-120, it's solid state input and power amp and the cleanest possible input gain staging, even without using the neutral tone stack. Problem is it's not tube power amp. I know FAS can't give access to the power amps without anything in front of them, that's why the wish is to make it into an amp.