Tony Salva makes special modifications from Randall MTS modules. The original modules are rewired, components are removed and changed. The goal is to make pre-amps which creates the same sound as some legandary amplifiers as Soldano, Marshal, Diezel, Orange, Vox and others.
Many of Salvation mods you can find in studio of Michael Wagener (Metallica, megadeth, Accept, W.A.S.P, Overkill, Ozzy Osbourne,…)
Here you can see Michael Wagener’s studio with Salvation mods inside Michael’s racks.