Best modern 6550 tube for ARC per-amp

your $15,000 p-o-s minnesota made linestage has a sucky, marginal PS circuit that requires a gold-plated, absolutely best sounding tube (when used in a totally different application) to sound its best!!! yes -- be sure to get your money’s worth now... remember, we can’t take it with we when we expire, right?

now excuse me, need to join my fellow parrots as we listen to some birdland :)

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Why the smiley face at the end? It’s obvious to me you’re being "Mr Know it all". You do have a way of just sounding like a special JERK... Fancy comebacks and all.
YUP That's you, Mr. Yourassholyness, I bow to your crappy reasoning, but I’ll pass on the rude delivery. You need to learn some manners, they don’t cost, they only pay... We can really get nasty if you want....I prefer you learn to be a Gentleman, not a Jerk... Your call.. Your information is overshadowed buy your fragrant continual sarcasm, you keep spewing, at anyone and anyone will do"

Non of the 15,000.00 comment or the sucky PS statement were called for... Learn some figgin’ manners.. No why not, BUT how can we....

Broken record.. Eeyore  or Winnie the Pooh

ARC used the Russian SED "winged c" 6550 tubes. These may no longer be available. A good alternate would be a NOS Sylvania or Philips 6550. 

Sophia audio makes some very good sounding tubes. And for a bit extra get a year warranty.

That's another thing I like about JJ, besides the sound quality, which is very near the top, you get a price that is very near the bottom.   
Almost all Tubestore.com tubes come with a 90 day warranty. The warranty on their Preferred Series is 6 months. I have never in nearly 30 years had a tube fail between 90 days and a year. In fact, I don't ever recall a tube failing in under 2 years, except for a couple Preferred Series tubes that blew within one month! The only tubes I would strongly advise against, had the best warranty. The extra you pay would seem to be for the warranty you will use. Hard to imagine anyone seeing the way mine failed would consider that worth the risk.   

All the many others, if they make it past the standard 90 they probably will go a good long time. Paying extra for a one year warranty in other words is a good profit center.

just a note to the op - who is seeking info here

don’t mind us tired old hacks here on this board doing a little keyboard jousting in the late night... some joust better than others when scotch or burgundy or ........ is involved  :)

what you will hopefully take away substantively from here is that given the ref 6 uses the 6550 in the ps voltage regulator function (and not a primary signal amplification function) replacing that tube for hopes of better SQ is a ’maybe’ proposition - certainly more of a 'maybe' than upgrading the tubes actually handling the music signal (even though that can’t be done on your unit given the 4x 6h30p’s...)

but yes, in practicality, it all matters (more or less is the main issue at hand) and it is just one tube, so it’s hard to waste too much money chasing a ’maybe’ in this case - i would still suggest checking in with greg at arc to get his take/advice - they made the amp, their input is valuable

my post below was only sarcastically referring to your ref 6 as a p-o-s -- hopefully you don’t take that seriously, we all know it is a lovely piece, one of the very best - i have the ref 3, love it, can only imagine how sweet the ref 6 sounds

cheers and good luck