Ruby el34s sound flat?

I've found the Tesla tubes to be more musical than the Ruby EL34.But you really can't tell if they're not broken in enough.♫

Ruby doesn't make tubes, they rebrand them like most of the sellers do. They would benefit from a good outgassing burn-in, especially if they are Chinese. Leave the amp on for 24 hours.

Any Ruby I had was Chinese.Sino?

I can't speak for the Rubys. I'm currently using JJ E34L (not to be confused with JJ EL34, they are not the same tube) in my Quicksilver Silver Sixties with the Gallo 3.1's and they sound excellent. Quicksilver recommends the JJ E34L as a replacement in the Silver Sixties. They sounded good right out of the box. If you don't hear a marked improvement after 40-50 hours I would try something else or you can give Mike Sanders a call at Quicksilver. He has always been very helpful.

They need time...........be patient.