Srajan's reviewed a older version of the Cabernet Dual. The review version used the 6sn7 tube for the low frequency. The most recent version (manufactured Dec '07) uses a 6H30 for the low frequency stage. There is a master control pot on the front of the chassis and a low frequency pot on the top of the chassis in between the 6H30 tubes. On the rear of the unit there are no gain controls, just a switch for xlr or RCA output.