Good tip Matt.. But I didn't buy these. They were the "new" ones that came with my RM100 when I bought it here in 2010. There was a mix up and they were sent afterwards, I had already installed a matched JJ set I had, so they just sat in the spare tubes box.. I may put these in my RM100 as I can bias them individually and use the matched JJ's in the RM50.
Honestly, it's not that huge a deal. I really just want to see the difference between the Mullard EL34 pair that came with this RM50 and a pair of 6L6's. This is the first time I've ever had EL34's. The EL34's sound really smooth and clean. I tend to lean towards a more raw crunchy sound. But it may not make much of a difference anyway as I don't play that loud. Could be pissing in the wind, where as I should just play it and stop messing around.. lol