We don’t use cheap Class-D chip in this amplifier. It is an “old school” Class A/B integrated amplifier when we use two tubes as preamp stage. It is fast, yet has the distinct smooth/warm tube flavor.

The headphone output is pure tube driven. You will have two choice — a pair of matched Chinese made 6J1 NOS tube or the western equivalent — a pair of matched Military grade 6AK5/5654 tube. We have acquired a large quantity of 1950 era Tung-Sol 6AK5/5654 tube directly from an US military base. Based on my testing, the headphone amp output on this amplifier along, is as good or better than a lot dedicated headphone amp on the market.

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.