The symbol is hard to see on the pictures usually, but if the tube says Mullard and Made in Gt Britain I would think it is the real thing. At the end of each listing bottom left you have a box to click on to ask questions. Just click on the box, go to questions other, and ask the seller.
In my experience most sellers will answer within a day or so and tell you the facts.
First post on this forum! I bought the EF95 CV4010 made by Amalgamated Australia and they are marked "SDA" ($8 shipped). I just tried them last night on my LD MKIII and the sound was immediately superior in every way to the stock driver tubes. I was listening to Diana Krall's "Girl in the other room" album in high-res (bought on HDTracks) and I could hear a fuller sound, more bass (slightly woolly perhaps for now), sweeter midrange and lovely highs. I used to think the stock tubes were great but these are sooo much better!
I can't explain why your experience is so different than mine. I use the LD as a pre-amp rather than as a headphone AMP. My setup includes a Wyred4Sound power amp and Dali Helicon 400s... I can't wait to burn these tubes in to see what happens (if anything)... If the real Mullards are better than these Amalgamated, wow!
Edited by audiophile noob - 11/30/11 at 11:14am