Appreciate the input from SteveFord and FullRange Man on this specific tube. Re the comment on use of impulse tubes - my phono stage uses 4 tubes ( two of the 6C45 and two 6922 ) I easily found a great range of options on tubes for the 6922 but posed my question of the Sovetek 6C45Pi as it appears they are limited. Being new to tubes I will research further and look into why the use of rectifier tubes. Thanks...