ARC Ref 6 tube replacement

I replaced in my REF 3 the small tubes by 6H30P-DR super tubes and the one in the powersupply by a NOS Tungsol 6550 blackplate , the are no better replace tubes imho . 

hansk46 .... Do u mean there are no better replacement tubes than those you mentioned? If so can you explain the difference in sound with the NOS Tungsol 6550 blackplate compared to stock power tube? 

I spoke with a BAT rep last month. He said "No more DR tubes available".

The Ref 6 uses 6H30P tubes, which is a Russian tube that has no substitute.  The older DR version is considered to have better sound, but they are very expensive and rare.  So unless you're willing to pay the price for the 6H30P-DR, there's no tube rolling for the Ref 6, except for the 6550, of course.