Gthirteen thank you for all the info. my buddy is ordering the amp monday and needs to tell them 6550 or KT88, I do not think the el34 is an option with Rogue but it is worth asking them about. I was thinking the KT88 usually had better midrange and the 6550 was more extended, actually your description is about exactly what I thought the difference was but my friend had heard the exact opposite.
thank you again
Phil
thank you again
Phil