From what I read the red base RCA were hyped up by a retailer that had a lot of them, and as Gibosi mentions, a lot of people don't think that they are special at all. Since we do not have any preconceived ideas on this forum what is the best sound, we can perhaps look or listen more objectively.
I ordered several lots of 6SN7 tubes when the price was right in order to become familiar with them. Any 60's Sylvania 6SN7GTB sounds very good, and also RCA 6SN7GT tubes with a little horizontal heater wire on top of the top mica. These tubes can be found for $5 or less with a little patience. In addition, these tubes are long lived - 10,000 hours, and so far I have not bought any that did not work. They are very simple to use - just plug and play.
Tried a couple of inexpensive Russian tubes, but in the long run I find that I am always coming back to US made tubes as better sounding, at least to me.
Edited by mordy - 6/23/14 at 10:06am