Audio Note UK manufacture a complete range of valve power, integrated and pre-amplifiers, offering over 40 base models with several variations each.

AN UK Level Amplifiers
Level 0 Class AB Push-Pull Pentode or Tetrode
Level 1 Class A Push-Pull Pentode or Tetrode
Level 2 Class A Single-Ended and Parallel Single-Ended Pentode or Tetrode
Level 3 Class A Single-Ended, Directly Heated, Zero Negative Feedback Triode
Level 4 Class A Single-Ended, Directly Heated, Zero Negative Feedback Triode
Level 5 Class A Single-Ended, Directly Heated, No Feedback Triode
Level 6 Class A Single-Ended, Directly Heated, No Feedback Triode
as Level 5 but all-out versions with no expense spared on parts

An Audio Note system may be composed of products from different levels, though it is best to base the system on the level of the amplifier, and introduce components which are no more than one level above or two below the level of the amp.