With tube amps, unless you get 100% of your tone from your preamp (like your mako) you're always gonna be dependent on volume. Part of why the Marshall 2203 was such a rocking sounding amp when cranked was because it was essentially identical to a Plexi but the two "channels" (hi and normal) are running in series rather than parallel. That's most of it anyway. The MV is really primitive but that's not the reason they need to be loud. They need to be loud because they're sill basically a Plexi, but they've got a little bit more gain coming from the preamp vs. a plexi where it's a clean preamp and the PI and power section are crunching.
If you add just one more gain stage you can get quite a bit more saturation at low levels, but you lose the magic touch and tactile feedback you get from the Plexi lineage.
Does that make sense?
FWIW I add a PPIMV plus the regular MV when I build one and it makes them much better. A depth mod is another worth while mod.
I remember a friend of mine stating that the bogner fish sounded more marshall in the preamp alone than any other marshall he played and he did have a lot of marshalls. I think he discussed it with alex flouros or something and he thought the same?
I always wondered why exactly Van halen chased so much preamp distortion in the 5150 series. And if all of the package can be moved to the preamp a bit? Taking the power amp by a percentage out of the equation. Personally I wouldn't have any trouble accepting the power amp as a dynamic filter, a compressor of sorts combined with another gain stage. This of course IS by definition touch sensitive at full tilt, as the signal varies by your pick attack.
Why not adding that to the preamp topology and feed it to a more controlled power amp...
I'd want dynamics ideally to translate the playing as an acoustic guitar does (a good one at least), letting the attack and the way you play do the shaping instead of choosing a "marshall" high mid or a "mesa" strong low mid voice to boot but perhaps that is just me. I am really tired of hearing the marshall thing going on or the boogie thing going either as a player or as a listener, all the time.