I inquired about purchasing a back-up set of tubes and was told to buy directly from Aries Cerat, or a USA tube dealer I trusted. Are any of you Helene or Kassandra owners buying tubes directly from Greece and if yes, is it easy? Also, I thought I would pick up a lower priced back-up set just in case a tube died unexpectedly. and I found Russian 6J11P-E pentode tubes for just a few bucks and JJ GZ34 / 5AR4 rectifier tubes for $22, so a full retube (emergency) set for about $35.
Beyond that, do any of you have recommendations for tubes in the middle ground between cost and performance, something reasonably inexpensive without giving up too much in sonic quality to better tubes. I have read recommendations to leave the Helene powered up all the time for various reasons like reducing cycles of tube rush and because of a long time required to warm up the unit before it sounds its best. If I keep it powered up most of the time, I don't really want to spend $300 per tube. The rectifier tubes seem to be mostly under $100 but then jump up into the $300'ish zone for better NOS tubes. The input tubes (E280F) can be expensive and harder to get. I understand it is possible to also use E180F, E810F, 6J11P, and D3A tubes with pricing covering a wide range. What are you all doing?