I
think that's different. I'm less familiar with real vintage HiWatts, but certainly on a 4-hole Marshall (and things that they directly imitated, e.g. Fender Bassman, or that directly imitated them, like Laneys of the same era) you've got a "bright" channel and a "non-bright" channel, each with a low-sensitivity and a high-sensitivity input. I think various Vox AC-30 models had 4-inputs, but I am less certain about how they worked; I think some models had separate "normal" and "vibrato" channels, while others had "normal" and "top boost" channels.
AFAIK, the
JH Gold (basically the Hendrixized JTM 45/100) models the high-sensitivity inputs (I assume) on both the "bright" channel and a "non-bright" channel. You can chose the channel with a switch on the GUI. There is also a GUI "
Bridge" switch, which lets you simulate the effect of jumping the low-sensitivity input from whichever channel is selected to the high-sensitivity input of the other channel.
The
HiAmp lets you switch between a "bright" channel and a "non-bright" channel using interface switches, but there are no options for jumping from the other inputs.
The
'59 Bassman model only simulates the 'bright' channel (though the GUI shows a non-functional additional input); so, there's nothing to jump in this model. (Other AmpliTube models of Batsman's ... Bassmen? Well, they don't have additional channel/input options either.)
I
think the only 4-input amps that are really in any way modeled in AmpliTube are the
JH Gold (the most "realistic" in terms of controls), the
HiAmp (next most "realistic" controls), the
'59 Bassman (only 1 channel), and perhaps some of the AC-30 models (though I think none of these model channel jumping) Technically, the original
British Lead S100 model represents a 4-input Marshall, though this is basically an older model that was effectively replaced by the
JH Gold.
The
Vintage Metal Lead is basically a later '70s, early master-volume Marshall, and those had two inputs in real life, I think. As best as I remember, most Marshall heads (Super Lead, SuperBass, PA, etc.) from the later '60s to the introduction of master volume controls around 1976 had 4 inputs, but none of these are explicitly modeled in AmpliTube.
As mentioned, early Laneys (which were basically copying Marshalls) likewise had 4 inputs, but there are no Laneys modeled in AmpliTube either.