RAM Tubes Online Store › 6BQ7 (RM-200 MkII) Image 1 of 1 6BQ7 (RM-200 MkII) $50.00 This is the NOS Sylvania 6BQ7 driver tube used in the Music Reference RM-200 power amplifier. Quantity: ADD TO CART Added! This is the NOS Sylvania 6BQ7 driver tube used in the Music Reference RM-200 power amplifier.