WARNING VALVES AND FUSES CAN FAIL AT ANY TIME! From time to ime put pat and preamble valves may fall Most users find regular valve stapler th lie of Benita 16 the Gen upkeep and venerability of the amplifier We suggest that you always have spare valves available as replacements in the event of a wail Tails. Every Clinician Class Ab Amplifier will quiver re-bossing when its output valves are replaced.