What made you change to a 6SN7 preamp?

Andy will guarantee there are as new and work , return I don’t think so

Brent Jesse has a return to fit your audio for 30 days plus you can take out up to 2 year insurance with  Brent if a tube fails for little money 

What Is Your 100% Money Back Satisfaction Guarantee? Individual service and customer satisfaction is paramount to VTS. Every tube purchase is backed by my guarantee. If for any reason you don't like the tubes, you can return them within 20 days of receiving them with generous exception if notice is given. Tubes are guaranteed 90 days against manufacturing defects with the exception of 6DJ8 type moving coil phono input tubes and certain rare models that simply chew up tubes.

What Is Your Return Policy? A decent sized square box of at least the size they were sent in is proper. Any tubes returned in padded envelopes or "little flat-ass" (video tape sized) boxes will be returned to sender and charged accordingly.

Thanks @audioman58, I should have just went to the Vintage Tube Services website.

In building preamp amplifiers, the 6SN7 based tube in general is a warmer sound, more relaxed presentation, more dimensional soundstage with real mid-range beauty.  That being said, the 6DJ8/6922 is generally more dynamic, faster, better clarity, and more slam.  It is a more upfront presentation.

Each one has benefits that may attract a person to that type of sound.

Being very new to tube amps and preamps, your description of those tubes is a big help. Regardless of what subjectively pleasing sound tube electronics may bring, clarity and accuracy, not mellow, syrupy, embellished sound are essential. I bought the DS2 preamp upon strong recommendation by an advanced DIYer of tube and ss power amps over at diyAuidio.com. I will use it to alternately drive my First Watt F4 and J2 power amps for the new my > 93db speakers I am building. Perhaps one or both amps will prove to sound better driven directly by my DAC. But for the neutrality and accurate imaging I want to achieve, how much can this be optimized without consequence by with the choice of 6SN7 and/or other tubes with this preamp? 

Comparing with a few friends who had the same tube amps as mine, they were running the 6922/6DJ8 preamps, and I eventually decided to go down the 6SN7 preamp route instead.  

I'd tend to agree their 6922/6DJ8 preamps sounded a bit more up front, and forward. More dynamic, yes, maybe so.  In contrast, I found the sound stage to go deeper, more layered, and not so forward with my quad 6SN7 tube preamp. A little more immersive if that makes sense. I could see benefits to both, for different reasons. Like many things, probably comes down to personal preference.