Would also love to hear about differences people have heard when using higher end amps / preamps with the rarer, and less obtainable NOS tubes.
I’m currently running a set of first issue Telefunken 7DJ8 and a set of Philips 1955 EL34 metal base in an amp. I am thinking about trying to find a set of unobtainium Siemens CCA or the like, but just not sure if they’re worthwhile if I could find them.
In the past, maybe 10 years ago, I would have said yes in support of NOS tubes. Because newly made tubes were an after thought in a dying industry. Now, I am not so sure for the following reasons:
Newly manufactured tubes have come a long way, both in terms of quality, reliability because of manufacturing process, newer and better materials. Any difference you hear is down to preference and not because NOS tubes are better.
There are less and less NOS tubes on the market. What is readily available are not the best examples. Unobtainium is now used more often and people are resorting to NOS tubes just because they are NOS even though they may not be great. Not to mention the issues with finding a matched pair or quad.
There are so many fakes and remarked tubes on the market it’s almost not worth the risk.
It’s not unusual to spend a ton on a NOS tube only to have it die after a few dozen hours. Then you are pretty much out of luck.
Modern tubes like the new WE300B or Takatsuki 300B hold up really well and in a lot of ways outperform NOS tubes.
That and look for 6l6’s