Let me put my 2 cents on the available tube replacement candidates for our Tube Magic and Tube Magic D1 DAC.

The DAC uses a Chinese made NOS 6N3 tube, which is a clone for western 5670 tube. There were quite a few factories manufacturing 5670 tubes in the past. Even for the same factory, there have been different versions. For example, GE, Sylvania, Raytheon, WE (Western Electric) they all made 5670 tubes.

It is believed western made 5670 has better sound quality than the Chinese/Russian clones.

For a start, you can try GE and Sylvania JAN (Military) version 5670 tube. They are widely available and reasonable priced. I believe most our customers replacing the stock tube with GE/Sylvania JAN tube. You can expect a certain degree enhancement on sound quality.

GE 5 stars 5670 tube

GE 5670 JAN tube

For better performance, you can try WE396A or Raytheon windmill getter, they are more expensive than above 2 models. The WE396A is probably the best one, but it is also the most expensive tube ( ~ $40 per tube).

Raytheon Windmill Getter 5670 tube

There is also Russian 6N3P-I, a 5670 clone made for Russia military. I’ve never tried this tube and don’t know if it is any better than the Chinese tube used in our DAC. The Chinese tube comes with the DAC was manufactured by Beijing Tube factory in the 70’s for Chinese military.