I recently purchased the vintage package for my Vibro King and just gig tested it last night...I am totally blown away by the performance of my amp. It went to a completely new level. Even the reverb sounded better than usual. These tubes are a little pricey, but worth it if you are after the best tone you could possibly attain. They turned my amp into a snarling beast! As some of the tubes are NOS, I am considering buying a second set to have around when I have to replace these down the road.