Are you talking about the Road King?
If so, it does sound pretty dang good... But it still sounds like a rectifier.
EL34's have more hi-mids and a tighter low end, but not as low. The 6l6's have lower low end, but it's loose and it has a top end sizzle and a more low mid throaty sound to them. Combine them and it' sounds a bit more evened out and more aggressive, but not everyone is looking for that tone. I happen to like it, sounds massive on rhythm guitars and smooth as silk on leads.... best of both worlds. :wink: . But like I said, it still sounds like a Dual Rectifier in the end (which is a good thing).