I asked earlier for opinions on the Sylvania 6080 and got some helpful responses, but just ended up buying two variations of the tube to draw my own conclusions.
I ended up getting a triple mica, yellow lettering (early 70's?) version of the tube, basically same one as in pic from
@MDR30, and what I assume by the lettering and logo to be a late 50's to early 60's 2 mica 6080 Gold Brand version - same one as in pic from
@JKDJedi )
I liked both, but think the vintage 6080 Gold Brand is noticeably superior.
For around $15 USD the vanilla 6080 was far better than I expected it to be, given some feedback I had seen on the tube. It's a bargain at that price.
To my ears what you get by upgrading to the vintage Gold Brand tube is deeper / more powerful bass and better instrument separation. It just has a cleaner sound if that makes sense. This is not to say the regular 6080 is bad by any means. It's better than a number of similar tubes I've tried at a higher cost.
I am reselling the plain 6080 and one of two 6080 GB's I picked up since I ended up buying a matched pair, as there were not a lot of great options for singles (and my amp only requires one). The Sylvania 6080 Gold Brand is most definitely a keeper!
I would place the vintage Sylvania 6080 Gold Brand right up there with the Tung Sol 5998 and the Chatham 6AS7G as my favorite tubes of this type. Your mileage may vary.