Well, I guess I was just reading about them and it's more the circuit than the tubes with those particular ones. I guess EL84s are a bit spongier and darker where EL34s are a bit tighter and brighter with more headroom... sound right? But a couple people on the forums I was reading were saying that a 4xEL84 amp is pretty similar in tone to a 2xEL34 amp. Sound right? Sorry, I am just not sure, all the amps I have ever owned have been 6L6s and 1 EL84.