What made you change to a 6SN7 preamp?

@invalid  ok, did not see it as a quote. Will try again, Thx.  

@mglik same question, above. And did the tube reseller offer you a return, refund?

Ralph @atmasphere was my primary reasoning to try the 6SN7. No one is kinder, smarter and with incredible patience.  However, he hasn't been able to talk me into his class D AMPS yet.......

A week or two ago someone posted about removing the PreAmp from your system and go direct from the DAC . I tried for a week . It was clean, clear and had Dynamics  but........lacked  engagement . I of course but the pre back in the system yesterday . 

Ralph's UV-1 preamp gave me my first taste of 6SN7's. That small simple circuit produced a huge soundstage, music with weight, and layering of textures. I've moved on to another 6SN preamp and an Atma-sphere S-30 which uses (6) 6SN7 input tubes.

Vintage tube service tests them in circuit, he has many different components to test them in.

@invalid , thanks for posting this. Andy has pics of all his testing gear on the website. Many years of purchases and I've never had a microphonic tube. Also the lowest noise of all my tube purchases. 

I did not jump to a 6SN7 preamp for the tube but did so to upgrade at preamp and the one I picked happened to use 8 of them including headphone amp.  

It also uses a tube rectifier which also contributes to the sound as well as a resin encased R-core power supply transformer.  

I came from a 12AU7 based preamp (4 mu followers) and I never loved the sound despite lots of tube rolling.  I have several on hand from prior amps and preamps.  

The sound of the new preamp with stock EH 6SN7 was better than the outgoing preamp by a wide margin.  Much larger soundstage, a purer more refined sound that was more transparent and bassier at the same time.  

After several NOS tube and rectifier trials the overall presentation is just incredible.  

Lots of variables in the comparison but the 6SN7 tubes are part of the mix that got me here.