Mullard EL34 that sounds best

I have always read that caution should be used when buying vintage used or theoretically NOS from Ebay.  My own personal experience was buying some RCA black glass VT231s from some guy in France, and two of them quit working not too terribly long after I took delivery, and I took the rest of them out and put them in storage after that. 

Yeah, but he has an excellent and substantial feedback, and each tube is under $100, so I'll give it a chance. One tube to begin with.

Just can't spend that much on new Mullards from Tube Depot, though they have some other Mullards for $300 each new.

Besides, they only have a few tubes in stock, so it is not a long term solution at all.

Have you thought about trying Rays tubes?  I have not but if you believe the reviewers they sound very good.  Around $850 per quad for their reserve quality and $300 for the select quality and they’re warranted for 12 mo.

Never heard of them. "Sound very good" is not good enough for me. Either I will stay with SED Winged, that are alright, or will want vintage Mullards.

I have settled in on the old stock Mullard EL34 XF2 with the single O getter.  The XF1 version,I have not heard, is too expensive and hard to find anyway.  The XF2 OO getter is the early version of the XF2’s and said to be the better of the two versions but to me and my system I really can’t hear a difference.  With patience and luck I was able to acquire 2 quads of lightly used new testing tubes for $80-100 per tube.  They have been the best sounding EL34’s that I have heard but they keep getting pricier.  Good luck!