This is a good poll. I am only using Mesa tubes (and that's what I checked) as my amp was bought new in early December, so I might as well take advantage of the 6 month warranty on the tubes. In the time that I have had my amp, I have blown 3 5Y3 rectifier tubes, a ridiculous number. There is probably no other amp in the hostory of amp manufacturing that has had that problem. I have the forth in there now, and so far' so good, but I'm not holding my breath.
Customer support at Mesa told me that it was a bad batch of tubes, as my amp does not fall within the serial number range of amps that had tubes blow due to faulty resistors, which was apparently addressed a long time ago. However, they are not techs.
I have ordered another amp from another manufacturer and when it arrives, I'll be taking the LSS to the shop where I bought it for a check up. The Mesa 5Y3 that is in here now, is going about a week. I use a Sovteck as a back up, since the time when the first one blew. No issues with it. In the long haul, if I end up keeping the LSS, I don't think that I will deviate from it's stock construction, and recommendations. Too many tubes, too complicated in that regard. It's its own thing. Typical Mesa Boogie.