Tube rolling newbie- how to choose NOS tubes

I’ve purchased a xDuoo TA-30 dac/amp for my first tube rolling experience. From online reviews, I plan to tube roll in a Matched Pair of Mullard 12AU7.

Looking online, there are new reissued Mullard 12AU7, matching NOS tubes at various price points, years, features (like long plates?), and used tubes like on eBay.. This is confusing, how do I choose? Should the tubes be tested? Who should I purchase from?




 B E F O R E  you do anything, find out what the tubes do in the circuit:

  • do they provide gain or just buffer for cachet
  • are they used in a balanced configuration or single ended
  • if balanced configuration, are they actively balanced or fixed

NOS tubes can be gassy and take a while to come to life... or may never 😞

See 5963Match.png (605×341) ( and 5963MatchDelta.png (605×341) (

This is four NOS 5963 [similar to 12AU7] used as a driver stage in two amps. There are 24 possible combinations of these tubes. Each combination sounds different.

And read ieLogical Rolling


complete waste of time and money to buy nos or other tubes without significant run in time for your new component…. burn in, listen critically, discern where you want to go

I disagree with this. Many manufacturers of tube-based gear ship their products with the best sounding, current production tubes that are readily available and don't increase cost of materials too much. Their expectation is that you will roll tubes - pretty obvious, why else would you buy a tube DAC.

All you need to do is leave your DAC on for a few days, identify what you don't like or want more of (in my case it was a high-frequency harshness/sibilance), and try out some NOS tubes. 

+1 @lowrider57 I got my most recent tubes from Brent in less than a week, and that was only because he is really busy.

Talking the push from above comment i can add that most tube rollers forget, that current manufacturers create their gear with modern tubes for sound and characteristics in mind. Also they do not assume or expect that everybody will do tube rolling. They go with what is available at the time of production. On the other hand we are not certain that a NOS tube would bring vast improvement, many times it can be the opposite. This means proceed with caution, money spent elsewhere in the system can sometimes yield better results.

But you would not know if not trying and that is a part of the game.

But you would not know if not trying and that is a part of the game.

... of fleecing the uneducated.

Thanks all for your advice, I'm learning a lot.  This is my first experience with tubes so I'm in experimental mode to understand the sonic differences between tubes. I'll also be using my DAP as a SS desktop dac/amp to sonically compare.