Synergy OS Pre-Amp, Pre-Amp Module for Synergy System, Is based on the ""D"" Overdrive Special - one of the most coveted boutique tube amplifiers, 2 Channels, Tubes: 2x 12AX7, Controls: Bass, Mid, Treble, OD Level, OD Ratio, Presence, Master and Volume, Switches: Bright, Deep, Rock/Jazz, Dimensions (W x D x H): 17.8 x 14 x 3.8 cm, Weight: 454 g