Line 6 Original based on a Hot-rodded Marshall® JCM® 800.
Hot rodding would usually entail internal modifications to the amplifier.
This could just be changing the odd resistor/pot/cap value to change drive levels, tone etc…
Or it could actually be a change to the signal path itself, such as adding and extra gain stage or wiring two different inputs in parallel on older Marshall amps. Marshall with extra gain mod.
The original intent of the term “modded Marshall’ was to achieve the added gain without resorting to a pedal. For instance GnR album Appetite for Destruction, was recorded with a Hot Rodded JCM 800.
Hot Rodded Marshal JCM example, 12ax7 (ecc83) added, using triode: