Tubes for Manley Chinook

Recently bought "new" National 6922 tubes for my Manley Chinook. Thought sound was great before, but uncannily real now. Question is to buy two more sets of these tubes while available, or take the plunge into the Mullard, Ediswan, or Telefunken tubes. A set of 4 would cost close to 1/3 of the phono stage.
Tubes can be as much of an upgrade as the component itself. Prices continue to climb for premium NOS tubes. Talk to Andy at . He measures, matches and listens to every tube he sells.