I ran some old RCA el-84s in my '99 Tophat CR for about 3 years. Sounded SO much better than stock. Well, I finally decided they were a bit worn and after the post "studies", I went with the JJ el-84. I gig pretty regularly and the first weekend they were punchy, smooth and robust. That was 3 weeks ago. Now I am looking around at my amp and wondering who turned my treble down! Possibly the tubes have "burned in", like a set of guitar strings? Sound more like worn out, to me. I'm kinda bummed that this has happened so soon. The amp sounded killer 2 weeks ago. Has anyone else noticed this? In JJ's in particular?