I use Sovteks almost exclusively and have yet to have a problem. I have them in my old gibson, my boogies, and I have NEVER had one little problem with them. I have had
Groove tubes come bad out of the box before and actually cooked some solder runs on a 5150 that I had on my bench for a retube and bias. ended up rewiring half of the amp point to point. I guess that makes it a hybrid mass / boutique eh?

Probably could sell it for millions on ebay with the right "Romanoff" sales pitch.
I would suggest you experiment and try other people's stuff and ask what they use in their amps. Boogie has their own brand which in reality are Sovtek's that they match and grade to their own specs and rename... kinda shady to me, but I still love the amps. I have also heard good things about the
Electro Harmonix tubes lately. *In the end, let YOUR ear be your guide, take every recommendation with a grain of salt, ESPECIALLY from a dealer as they will tell you that it just so happens that THEY sell the best tubes and no others compare...salesmen...sheeeyahh riiiight....
sorry if this doesn't answer any questions, but its like asking someone what ice cream you should buy...
Bamm