Just thought I'd give you guys a heads up on my testing so far. Don't bother replacing the EL84 and 12AX7 in these amps. They sound very good with the 5 watter. I thought I had to have a JJ EL84 and Tung-Sol pre in there, but alas the JJ just doesn't sound as good as the more robust Chinese EL84. It has the Shuguang logo on it. A very robust looking and sounding tube. A little bright, but very musical. Great low end punch from this one. THe JJ really dissapointed me here. This Shuguang EL84 is new to me. I don't know of anyone selling these except under the TAD label. Well, Weber does, but he doesn't sell matched sets. The Chinese 12AX7 isn't bad either. Still trying to decide if I'm gonna keep it or the Tung-Sol in there.