I have a directory in which HD 540 is presented as a novelty. There are no Reference Gold which was done in 1985 and the HD 250 Linear 1986. But there are: HD 410 SL, 414 SL, 420 SL, 425, 430, 222, 230 and UNIPOLAR 2002 set. So I think they are of 1984, probably at the end of 1984.

The first HD 540 was made in 1984, so they have more than 30 years.

Your recommendations have made, that I bought  HD 224x and HD 222. In my opinion they are the worst of all Sennheiser headphones about which you wrote and whose I listened. Lack bass, have unnatural mids and  treble. I personally, definitely do not recommend these headphones.

  HD 540 II is an excellent handset and are much better than, for example. Dnon AH-D7100 or Sennheiser HD 600. However, in my opinion, the HD 540 and 600 ohms are better. Regardless of the used pads. I have used in comparisons of all pads, I changed them. I think the same as you about HD...

For me, the HD 540 sound best in a configuration HD540+ Luxman L-530 (The Class-A operation 2 x 15W) + Marantz CD 60 Scorpion (TDA 1541 NOS DAC, output tube). Such a system is powerful and fast bass, mids beautiful and a very large and wide soundstage. HD 540 need a good amplifier with a...

It's hard to remember everything, it was 30 years ago

  They aren't perfect, but really very good to listening all kind of music ;)

  If you want, I'll send you the scans Sennheiser catalog of 1984?

The pads verur is with HD 540 Reference II

Anno Domini 1984  

This is original old HD 540 headband.

Thanks o0CosmoMemory0o   ;)