It was me. I have absent from Head-Fi for a while.
I have run a few pairs of the Elrog's and had issues with most of them. There was a lot of back and forth between the then manufacturers of the Elrog, myself and Jack Wu. There was various speculation about the bases and other issues of the tubes and Elrog countered that with a suggestion that my 234's were not specced to run the tube correctly (even though by then I had run up a few thousand or so hours of use with other 300B's with no issues).
Fast forward, and I now am a Senior Contributing Editor for Mono and Stereo (sounds flash but I am just a scribe) so have access to more information.
The company that started Elrog ran into financial difficulties last year and was purchased by Thomas Mayer from Vinyl Saviour. Thomas is a savvy operator and has built many amps around the Elrog tubes successfully. He has been in contact with me recently and if you go to his site (Vinyl Saviour) and read his blog you will see he has completely re organised the manufacturing process of the Elrog Tubes. There were a number of issues which contributed to their earlier failures. Production has now restarted of the tubes and I have a set of the new production Tubes on the way. On my end my system has changed a fair bit so I eagerly wait to try out the new Elrog 300B's.
I will say this: What was so frustrating is that the Tubes sounded bloody marvellous, its just that the reliability was not there. Thomas tells me that not only has the reliability issues been sorted out but the the sound has been improved a lot.
This is all music to my ears and hopefully to anyone else that got to sample the old Elrog's. We need more new production Tubes. When I receive my set and they have some time on them I will report on their progress.
I am currently running a set of the new KR HP Tubes, the 300B Balloon's and the 274B's. I am at 350 hours and they replaced the Takatsuki 300B's and 274B's which were running in the amp before then. I am more than impressed by the sound quality of the KR's - I draw special attention to the fact they are the new HP versions. These were designed in unison with Joe Skubinski of JPS Labs - Abyss fame and I am told specially tuned for Headphone use. What ever the result is outstanding and I have no issue recommending them wholeheartedly and yes I paid full freight for my pair as I have the Elrog's.
Due to the construction and materials of the Elrog's, they require careful handling. My current plan is to run them with either Takatsuki 274B or KR 274B rectifiers.
I believe Woo Audio sell the KR HP Tubes. Just make sure you get the HP versions, they have a white base.
Photos below.