Mesa Boogie's Express 5:50, features a duet of 6L6 power tubes. It features Mesa’s Duo-Class power switching circuit. The switching circuit allows the player to choose between Class A/B at 50 watts or Class A at five watts. Peter Stroud, musical director and guitarist for Sheryl Crow, PG columnist and tone chaser extraordinaire, shed some light on this subject and put it into terms that are easy to understand: “When the amplifier is in Class A mode, it is being pushed much harder – think of it as the power section on ten, full throttle – providing more break-up, midrange and sag, which is great for that vintage, bluesy rock vibe. In A/B mode the power section provides much more headroom, producing tighter low-end sounds and a more prominent top-end.” The 5:50 offers the player two separate channels, each with two modes and independent EQ. Channel 1 provides Clean and Crunch while Channel 2 provides Blues and Burn. Other features include a tube-driven reverb and separate, footswitchable Contour knobs for each channel.