One of the most iconic amp sounds of all time is of course a cranked British stack. It is and always will be the sound of rock. From the moment in the 1960s when these amps were created to keep up with the likes of Pete Townshend, Jimi Hendrix, and Eric Clapton, a revolution in thick-creamy overdrive was born. Since that time, there have been a string of British amps so iconic that they continue to rule stages around the world.Originally developed to keep up with ever-growing demand for more volume and distortion from the burgeoning hard rock scene of the 60s, these Plexis have continued to define what rock guitar sounds like. With no master volume and the need to make up for the less-than-adequate PA systems of their day, the only way to get the most from your Plexi was to crank it to punishing volume levels. But if the ever increasing popularity of these amps is any indication, that s just how guitar players like it.The two channels of the Plexi module can be dialed in for jumping between a great rhythm and lead tone. While each channel s I and II controls work much the same way as jumping the inputs on the original amps, allowing you precise control over the shape of your gain. With the 12AX7-driven Synergy Plexi Preamp, you re adding the undisputed sound of rock guitar to your palette. The Synergy Plexi pre-amp features two channels, each with gain, Input I and Input II knobs. Both channels share a three band EQ.The Synergy PLEXI module includes a three position switch which allows you to configure the input tube bass response to match the original circuit of the selected module Patent Pending. Switch setting will will affect the feel and tightness.