VIVA NOS 6sN7’s.... three bad ones in a row.

so For the past couple months I have been searching for some really good NOS 6sN7. I have bought three pair of VT-231 “bad boy” tubes from a very popular online merchant. Each pair has yielded a faulty tube. The merchant has been cool about taking the returns and crediting my account, but I’m losing faith in their “all tubes are tested NOS. I mean two of the tubes rattled like they had broken bits inside and one just blew as soon as I plugged it in. I want the best for my setup and I’m looking for advice. I need a matched pair. My budget is flexible. 

MY SETUP:
NODE 2I > GUNGNIR MULTIBIT > FREYA +> AEGIR > Sierra 2ex. 
All connections are aq earth xlr. All power cables are synergistic. Furman Elite Pfi power. BDR cones and other tweaks.