I think Samuel makes a very valid statement, but their are some things that I would like to point out. First, their are independent tube sellers such as Upscale Audio, that perform the same tests as ARC and others. Second, you have to consider the cost of retubing. I have a CJ amp that requires 12 6550's, 4 6CG7's and 2 5751 tubes. CJ wants $700 for the tube package, and that's insane! I guess if I only needed a few tubes, I might consider purchasing from the equipment maker. The third premise is that ARC will only warranty their tubes for 90 days, same as a great many Independent tube dealers. I purchased my tube set from reliable and trustworthy tubesellers for less than half of what it cost to buy from CJ. The tubes are now over 2 years old with approximately 2500 hours on them and I have had to replace 2 6550's just last month.