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.
Ruby el34s sound flat?
I just put a new quad of Ruby EL34s in my Quicksilver Mid Monos. The highs are limited, the sound stage is smaller and it just sounds veiled. Is this just a bad choice for this amp or do they just need to "break in"? Previously I had Teslas. I am using Gallo 3.1's