REF5SE tubes

I'm not a past customer either (personal thing), but I did not go further than loading the items into the shopping cart.

Otherwise, I did not notice any exclusions for those particular tubes.

DeKay

I owned older ARC, before the 6h30, but run a line stage, the Veloce Lithio, which does use that tube. I had a NOS quad of the DR Reflektor which sounded better, and when I was "fettling," thought those might be past prime time; tried a set of new production from Russia and at least in the Veloce (configured as more up to date, with newer battery pack and circuit changes), the modern tube sounded dead and flat. I did find a quad of old never used DRs from the late ’70s that make music. I understand that some ARC users don’t hear that much difference between the DR (how old?) and modern Russian tubes- you are limited to Sovtek or EH as far as I know unless you plumb the depths-- and those can be counterfeit or late production. 

I say if you can’t hear the difference, you are probably fortunate. I think that tube is a dead end, given the difficulty of sourcing it.

I was able to acquire a full set of new matched tubes from ARC last week. (REF6SE) $1200 including shipping. I did have to wait a few months but my current set still have some good life in them. Good luck…!

I bought mine from Tube Depot and The Tube Audio store, same prices as Upscale, "matched" supposedly- though matching on these is not so important according to ARC and others (for power tubes it is though).

Having used both Tube Depot and The Tube Store in the past, I would highly recommend Brent Jessee at audiotubes.com.  

He is well respected and can give you his personal recommendations.