Excellent advice Mike. Nobody else tests their tubes in all the parameters that RAM Tube Works does. The details of that testing are available of the website. Roger Modjeski matched pairs and quads for Quicksilver (he and Mike Sanders were close friends and fellow admirers) and Atma-Sphere.
What is up with Audio Research during the pandemic?
I ordered a set of tubes for my ARC Ref 3 line stage on May 4, 2020. So far, no tubes, no tracking number, and no contact initiated by ARC. I did get an email response last week from them saying that they were "... working on getting caught up in the shipping department and have not yet shipped your tubes." This post is not to hassle ARC in the midst of a crisis. My hope is that all there are safe and well. Many "non-essential" businesses are struggling and frankly, I want to do all I can to support them. Music has been a wonderful source of comfort and enjoyment for me, now more than ever. I can wait, but I would feel better if I knew that the ARC folks were doing OK.